Information Week recently
posted an article suggesting that Firefox's market share has peaked, having slipped slightly in recent months and settling in the 7 to 8 percent range. I'd have to agree with that assessment (just by looking at
my own web site stats), though the number of Firefox users on my site is a bit higher than average.
The article also posted about Opera going free in an attempt to gain market share -- and, I agree here, also: too little, too late for Opera. They missed the window.
There are a lot of features I really love about Firefox. Not just tabbed browsing, but small things that only advanced users would typically use, like the user agent switcher, modifying the settings easily by typing about:config, etc. For intranet applications (and yes, I'm at Microsoft!) IE is just easier to use. Especially now that I'm using IE7, there's not much incentive to use Firefox anymore. I noticed my own usage slipping since I like the tabbed browsing in IE7 better, I can listen to LaunchCAST, and the network authentication set up is easier.
Most people point out that some (or all) of these things are possible in Firefox ... but you know, there's only so many hours in the day to fiddle with this stuff. I just need something that works.