Are you running a beta version or something? Because that's exactly what Chrome doesn't do with me. It autoupdates about once every six weeks, and the only reason I notice the update itself is because of news that the new version of Chrome is out. The update itself happens 100% in the background, and I can easily find information on it on the Chrome blog if I want.
Lately its been every 6 weeks, but before it was every few weeks. Firefox is even worse now. If you have multiple machines at home and at work(which I do), you get sick of it pretty fast.
And what seems like 100% in the background is just that...a Google updater running in the background 100% of the time. Just another .exe which uses up resources I have to deal with at startup.
Like IE does the same thing (hides behind windows update) however it doesn't do it as frequently so when an update happens, I want to see whats new and I don't mind to take the time to see it update...
FF and Chrome on the other hand use up my update patience points very quickly and don't provide many worthwhile things with each update.