https://www.mozilla.com/en-US/firefox/6.0/releasenotes/
Honestly seems more like a release for developers. The problem with firefox releasing like this is that they’re trying to compete with Chrome… but chrome users aren’t even aware when their software is updated most of the time....
https://addons.mozilla.org/en-US/firefox/addon/is-it-compatible/
This puts an addon’s compatibility versions right in your addons thing, and all of my addons have assumed compatibility for FF 7-12. Probably because all the developer has to do is type “compatibility = 7” in a file and it claims to work. I actually still haven’t updated from FF 4, but now that I see everything is compatible even with FF 6, I may as well update.
Still, I’d be interested in knowing what Chrome does differently with its addons from Firefox. Or does it just have different kinds of addons? If an addon doesn’t change anything that a browser update would (interface, deeper fiddly features) then it makes sense it would always be compatible, but those are the best kind of FF addons. Also, I have my addons set to update themselves automatically in FF 4, so I never know when I’ve gotten a new version of one. You can set the same option for Firefox updates, but I like to have control over that.