I am piling a list of notable service changes. I will not post all the changes at once though. For now, here are notable service changes for Bronx, Brooklyn, and Manhattan buses.
The Bronx
Bx6 LCL/Bx6 SBS
-SBS Service (as we all know) will start on September 3rd.
http://web.mta.info/nyct/bus/schedule/bronx/bx006cur.pdf
http://web.mta.info/nyct/bus/schedule/bronx/bx006scur.pdf
Bx12 Local:
- Orchard Beach Service has ended
http://web.mta.info/nyct/bus/schedule/bronx/bx012cur.pdf
Bx40/Bx42:
- All Bx40 goes to Fort Schuyler, All Bx42 goes to Harding Avenue
http://web.mta.info/nyct/bus/schedule/bronx/bx040cur.pdf
BxM2:
- Saturday buses from 11:20 AM to 7:20 PM towards Riverdale now depart 5 minutes earlier
Brooklyn:
B16:
- Additional weekday service added for the school semester
http://web.mta.info/nyct/bus/schedule/bkln/b016cur.pdf
B47:
- The 12:25 AM and 12:55 AM trips from Kings Plaza have been consolidated into a 12:40 AM trip (Tues-Sat)
- The 11:30 PM trip from Bedford Stuyvesant will now depart at 11:44 PM (Mon-Fri)
- The 12:00 AM trip from Bedford Stuyvesant has been discontinued (Tues-Sat)
- AM rush service to Bedford Stuyvesant runs every 8-12 minutes instead of every 10-15 minutes
- AM rush service to Kings Plaza south of Rutland Road 
every 6-8 minutes, every 10-12 north of the instead of every 8 minutes and 12-14 minutes, respectively
http://web.mta.info/nyct/bus/schedule/bkln/b047cur.pdf
B52:
- Midday service runs every 10 minutes instead of every 8-9 minutes
- PM rush service runs every 8 minutes instead of every 6 minutes
- Early evening service runs every 8-12 minutes instead of every 15 minutes (Mon-Fri)
- Late evening service runs every 30 minutes instead of every 20 minutes (Mon-Fri)
http://web.mta.info/nyct/bus/schedule/bkln/b052cur.pdf
B61:
-Early AM Shoulder (5-6 AM) runs every 20 minutes instead of every 12 minutes (Weekdays)
- Service from 6-7 AM operates every 10-12 minutes instead of every 7-8 minutes (Weekdays)
- PM rush service operates every 10 minutes instead of every 8 minutes
- Early evening service operates every 15-20 minutes instead of every 14-15 minutes (Weekdays)
- Late evening service operates every 30 minutes instead of every 20 minutes (Weekdays)
http://web.mta.info/nyct/bus/schedule/bkln/b061cur.pdf
B63:
- The 4:50 AM and 5:15 AM trips to Brooklyn Bridge Park have been consolidated into a 5:00 AM trip (Wkdys)
- The 6:44 AM trip to Bay Ridge has been discontinued (Weekdays)
http://web.mta.info/nyct/bus/schedule/bkln/b063cur.pdf
B65:
- Midday service runs every 30 minutes instead of every 20 minutes (weekdays)
- Early PM shoulder service runs every 20 minutes instead of every 15 minutes (weekdays)
http://web.mta.info/nyct/bus/schedule/bkln/b065cur.pdf
B70:
- The 6:56 PM and 7:16 PM trips to Dyker Heights have been consolidated into a 7:05 PM trip (weekdays)
- The 8:10 PM and 8:30 PM trips to Sunset Park have been consolidated into a 8:20 PM trip (weekdays)
http://web.mta.info/nyct/bus/schedule/bkln/b070cur.pdf
B83:
- Service operates every 10 minutes during the AM rush instead of every 7-8 minutes
- Service operates every 12 minutes during most midday hours instead of every 10 minutes
- Service operates every 10 minutes during the PM shoulder instead of every 8-9 minutes (weekdays)
- The 5:20 AM bus from Broadway Junction has been discontinued (Saturdays)
- The 5:57 AM bus from Gateway Mall has been discontinued (Saturdays)
http://web.mta.info/nyct/bus/schedule/bkln/b083cur.pdf
BM4:
- The 6:40 AM Midtown ALL STOPS bus will now depart at 6:30 AM (Weekdays)
Manhattan:
M1:
- Service extended to SoHo
- SB service from 2-3 PM operates every 6 minutes instead of every 7 minutes (weekdays)
- The 10:25 PM and 10:45 PM trips to Harlem are consolidated into a 10:35 PM trip (Mon-Fri)
- An additional 4:00 AM trip added from Harlem on Saturdays
- An additional 4:59 AM trip added from Harlem on Sundays
http://web.mta.info/nyct/bus/schedule/manh/m001cur.pdf
M4:
- Service from 8:59 AM to 9:37 AM operates every 9 minutes instead of every 11 minutes (weekdays)
- The 5:35 PM trip from Fort Tryon Park will depart at 5:37 PM and will not run between 135 St & Penn (wkdys)
- A new 5:05 PM to Fort Tryon Park from 135 Street has been added (weekdays)
http://web.mta.info/nyct/bus/schedule/manh/m004cur.pdf
M10:
- Service operates every 10 minutes instead of every 7 minutes during the AM rush
- Service operates every 15 minutes instead of every 12 minutes during midday hours
- The 7:45 PM and 8:00 PM trips to Columbus Circle have been consolidated into a 7:52 PM trip (wkdys)
- Service from 7-8 PM to Harlem operates every 15 minutes instead of every 11-12 minutes (wkdys)
http://web.mta.info/nyct/bus/schedule/manh/m010cur.pdf
M15 SBS:
- AM rush service operates every 2 minutes instead of every 2-3 minutes
- More AM rush service towards Harlem from South of Houston Street
- An 11:15 PM trip from South Ferry to Harlem has been added
http://web.mta.info/nyct/bus/schedule/manh/m015scur.pdf
M22:
- Early AM rush service operates every 15-30 minutes instead of every 10-20 miutes
- Early evening service operates every 30 minutes instead of every 20 minutes
- PM rush service operates every 15 minutes instead of every 10 minutes
http://web.mta.info/nyct/bus/schedule/manh/m022cur.pdf
M31:
- Less frequent AM rush service
- PM rush service operates every 8-10 minutes instead of every 7-9 minutes
http://web.mta.info/nyct/bus/schedule/manh/m031cur.pdf
M34 SBS:
- Certain M34 buses will originate/terminate at Waterside Plaza. These buses will turn down 2nd Avenue, and will go up via FDR Drive.
- Frequencies for Waterside Plaza M34 is every 74-125 minutes during middays, every 20 minutes during the PM, every 20-120 minutes during evening hours (although almost always 30 minutes), 14 trips each direction on Saturday and Sunday
http://web.mta.info/nyct/bus/schedule/manh/m034scur.pdf
M57:
- More frequent PM rush service
http://web.mta.info/nyct/bus/schedule/manh/m057cur.pdf
M66:
- AM rush service operates every 3-6 minutes instead of every 4-5 minutes
- PM rush service operates every 5-6 minutes instead of every 3-5 minutes
- Evening service operates every 15 minutes instead of every 12 minutes
- Most shortturns in the AM from Lexington Avenue to York Avenue discontinued
http://web.mta.info/nyct/bus/schedule/manh/m066cur.pdf
M72:
- Less service during AM rush and PM rush
http://web.mta.info/nyct/bus/schedule/manh/m072cur.pdf
M96:
-Less frequent service throughout the day on weekdays
http://web.mta.info/nyct/bus/schedule/manh/m096cur.pdf
M98:
- AM peak service operates every 10-12 minutes instead of every 8-10 minutes
- Service during late AM rush now runs every 30 minutes instead of every 15-20 minutes
- Service operates every 15 minutes throughout the PM rush in peak direction instead of every 12-15 minutes
- New 7:35 PM trip to Washington Heights added
http://web.mta.info/nyct/bus/schedule/manh/m098cur.pdf
M100:
- Less frequent service before 5:15 AM (weekdays)
- Service operates every 10 minutes during the height of the PM rush towards Harlem instead of every 8
- Some pockets of 10 minute headways during the PM rush towards Inwood span longer (instead of every 8 minutes)
Queens and Staten Island Service Changes will be posted up soon. Share your opinions with the poll listed above and/or in the comments below.