One thing I dislike about the custom CSS fonts is that they usually look really rough. For example the Typographica header - in my taste, no matter how beautiful the font is, the rough rendering kills the visual appeal and a common, but smoothly rendered font looks way batter [1]
What Browser/OS are you using? I ask because even when zoomed into a ridiculous level the font still looks smooth to me (Chrome+Mac).
I think the root cause may be covered in this SO Question [1] which fixes the problem on many sites by re-ordering font inclusion list so Chrome+Windows picks up the right one.
I know they're not common yet, but they will be someday. Designers often use the latest (Apple) hardware, so what looks good on their screens may not look good for everyone else. In some ways I see this as a positive—it helps push the industry forward—like PC game developers who require the latest $800 video cards for the best experience.
Retina is just a marketing term by Apple. They are actually displays with a high DPI. You could call them high DPI displays or high resolution (kinda misleading) displays instead.
Hunh. Does Chrome not use custom CSS fonts? It is falling back to Georgia on both Mac and PC for me (edit: with Ghostery running). Turnip is shown on Safari, Firefox and IE 8... and IE does an even worse job of rendering it ("rendering" is generous).
Edit: woops, the Adobe javascript was getting blocked by Ghostery.
[1] http://i.imgur.com/U5UObQh.png