No, cue the
you're assuming you won't get Xcode 4 with Lion rabble. Seriously. Don't jump to conclusions yet.
Can you clarify the $5-hurts-FOSS argument? I don't mean to sound crass, but there are people who pay more than $5 for coffee. If a one-time charge of $5 to build OS X versions of your FOSS project is a, as you say, "[sizable] obstacle" to entering FOSS development, that's a genuine surprise to me. Especially since Xcode 3 is still absolutely free. If I were a committer on your project I'd buy it myself and donate it, for crying out loud.
They anticipated this, undoubtedly, and put the button right there: "Looking for Xcode 3 because $5 is too much? Here it is!" You're really only paying for the improved GUI. Does your FOSS project use Xcode as its primary development platform, or is it just using the compiler toolchain?
This revolt to $5 is absolutely stunning. Even more worth thinking about is that all the commenting about it on HN equates to far more than $5 in billable time...how many copies could the revolting have purchased?