Sadly, Firefox 2 isn't dead (and apparently still accounts for 40% of Firefox usage), so inline-block is even further-away than the death of IE6. I recently had to take out a bundle of inline-blocks I had put in for a client's intranet site after finding out that they wouldn't even consider updating past 2.0.0.20. Why go through the major effort of transitioning to a new browser and then doing QA and testing for all your existing web-apps, but then not put in the small amount of effort involved in keeping said browser up-to-date? I've never seen a single site, no matter how complex, break on a Firefox upgrade.
Not sure where you're getting your 40% number, but my sites see less than 3% of users using FF2 (these are sites which still see 20%+ IE6 use, so not skewed towards developers).
Agreed, but Firefox 3 is quite different from Firefox 2 in terms of interface etc. and there are some quirks (such as the awesome bar) that at least among the people I talk to got quite a bad rap to start with.
