Yep, I agree with you Brettison. Ubuntu's update system is pretty awesome, but the problem is that right now it's only used for fixing of severe bugs and security issues. In order words, regular apps don't get updated.
Ubuntu devs are looking into that right now, mainly because of Firefox, because it's such an important app for Ubuntu and its release schedule doesn't align with Ubuntu's. They want app devs to be able to push updates to current Ubuntu releases and are trying to get this working for either 10.10 or 11.04 (I believe, haven't checked lately). Obviously, besides the big technical/logistical side of things there's also the huge security issues with this, so it might be some time before we can use it.
But alas, right now there isn't a great option to update apps besides ppa's (there's the
daily ppa for Firefox which has alpha/beta/testing versions and the
security ppa which contains 3.6.4).
Like you said, the Firefox .tar from the Mozilla website isn't exactly the greatest option. You'd have to replace launchers and everything (although I believe all settings/bookmarks/history is saved already). The security ppa seems like a good option though, I didn't know about it before myself, anyway.
(Sorry if I'm explaining basic info to you, this is just a general explanation also for people new to Ubuntu)
//Edit: here's the
related blueprint