As of September 2007 Firefox is at 35.4% wresting top spot from IE6 at 34.9% (and dropping) with IE7 coming a distant third at 20.8% according to http://www.w3schools.com/browsers/browsers_stats.asp
If only Microsoft had stuck to their word that IE6 would be the last stand alone browser from them in 2003 when it had 71.2% of the market, we'd be seeing IE's death by now. I guess it's Firefox's own popularity that prompted Microsoft to rejoin the browser wars.. ::)
I know IE7 will eventually take over, but let's enjoy this happy bubble of NON-market dominance while it lasts :)