This test page for text shadow and downloadable fonts renders the ring inscription using the private plane codepoint commonly used in the past (2nd and 3rd block) and the "draft" codepoint at 0x16000-0x1607F for the 4th inscription.
According to Rik, it displays fine in Safari 4 beta under OSX.
However, in webkit nightly and safari 4 beta under XP, the 4th inscription in BMP does not render.
I am a little confused by the terminology here (I thought 0x16000 was outside the BMP). The inability to display non-BMP characters on Windows is not specific to CSS3 web fonts, but I am not sure that there is a bug in Bugzilla about the general problem.
(My last comment was referring specifically to the Windows port used by Safari; the Chromium and Cairo ports may not have this issue).
I couldn't find any general bug about it.
I figured it might well extend beyond web fonts, but just thought I'd describe what I encountered.
You're right. Sorry. Should say SMP. Altered title.
I'm not so great on the terminology is clear :)
*** Bug 90337 has been marked as a duplicate of this bug. ***
This bug also happens for fonts installed on the system. See bug 90337.
*** Bug 122526 has been marked as a duplicate of this bug. ***