Here is a list I refer to all the time when I need to find out when a GP version came out and when support will end:
|Product Version||Product Release/Start||Mainstream Support End||Extended Support End||Link for more information|
|GP 2010 R2||07/14/2011||10/13/2015||10/13/2020||Link|
The links provided will sometimes have more information about Service Packs and support guidelines for a particular product.
Some more information on the Extended Support for Dynamics GP 10.0 can be found here.
You might also find this explanation of the Extended Support phase for Business and Developer products helpful.