Used IE7 all day yesterday, testing sites etc. It's a big improvement over IE6 (originally released in 2001). It will be pushed out in "updates" in November so everyone (who gets the updates automatically) will have it soon.
Of course, it's limited to windows, doesn't have the selection of exstenions Firefox has, the phishing filter sends info to MS, etc.etc.etc. But at least it's usable.