iOS Version History and details inside
I found this today. Thought some people might be interested in seeing. I myself when it comes time to do a new jailbreak, check to see what the new version has to offer and is the time and possible trouble worth doing. Trouble meaning getting the J/B phone back to what you had it at. From detailed themes to settings, activator, lockscreen mods. But anyway here is the wiki on the iOS versions and what they include. I think alot of people that are re-jailbreaking are forgetting we got 4.2 coming in the very near future. I still haven't made the decision to go to 4.1 yet but probaly will because improved battery life has been in the update along with a little better performance from the phone itself.
iOS version history - Wikipedia, the free encyclopedia