Looking at Platforms Supported by Selenium the highest version of selenium supported is v 10. I am assuming this is in line with 10 being the current extended support releas
You should refer to CHANGELOG. Thats always the latest. Seleniumhq.org gets updated by someone manually... Which is not happening regularly I guess.
I use selenium 2.25 and I had to download to Firefox version 14 in order to get selenium to work correctly. Other people have documented this issue but I haven't found any resources that say what versions of Firefox are supported for each version of selenium.
selenium-firefox-driver 2.25.0 not working correctly with Firefox 15
Also if you are using selenium with your web browser you are going to have to turn off automatic updates on your browser to prevent it from updating.