Unexpected impact of OS X
A surprising side-effect of MacOS X may be the liberation of Web typography from the constraints of Verdana and Times. Apple systems now ship with a range of real fonts; for example, Magdalen Power's weblog Fools Paradise gets a lovely archaic feel from Hoefler Text. You couldn't attempt this without GIF's last year; next year, this may be perfectly familiar. For now, though, there's lots of easy impact to be had.
Yes, the Mac's a minority platform. But if you can get lovely pages for a third of your readers and pretty good pages for the rest, it's a win. Plus, you know the MacOS X people have fresh, CSS-compliant browsers and plenty of rendering power.