I you look How Firefox 2.0 Will Be Marketed, you’ll see that they’ll run TV ads and push the functionality aspects rather the fact that it is free and open source. Thus they are entering the market head to head with Microsofts IE, where the Firefox-advantages are not necessarily that great in the long-run (Microsoft just needs to redirect some of their infinite monkeys from typing Shakespear to adding whistles to their new IE). What makes Firefox special is that it is open. That people can build upon it and derive new browsers from it. By going more and more mainstream Mozilla runs danger of giving that advantage away. Hey, if that tiny geek market is not large enough you should have a look who is going to install the web browser on their parent’s machine or in all the companies’ boxes. Mozilla, Mozilla, mind your origins and also keep in mind that accessible source code is not what makes an open source project open.
P.S. Found out about this through Dave Neary
UPDATE (2006-10-26): LWN (access with subscription only until next week or so) writes about the same issue and agrees that toning down the free aspect is the wrong way to go. Nicely written, check it out when it gets public.