Firefox is releasing new version every alternate month.
v4.0 on March 22nd, 2011 v5.0 on June 21st, 2011 v6.0 on August 16th, 2011
It can be because of the competition with google chrome.
But most of the addons are still aren't supporting newer versions. I realized this today when most of my addons stopped working when my Firefox was updated to 6.0.1
We do have option to increment the version but is there option to get back to previous version. Actullay this questions sounds like "i have windows seven and i want to go back to Win XP " :-P
Downloading previous version and installing it is the only option i see right now. but i dont want to lose Bookmarks,history etc.
Any comment is appreciated.