I have been using font embedding, of necessity, on my website www.bhurgri.com
for Arabic script fonts for last 8 years. But now font embedding has really entered a new age. Visit my following test page athttp://bhurgri.com/bhurgri/copy/testfonts4.htm
On Windows use Internet Explorer, Safari 4 or Firefox 3.5 and see font embedding working flawlessly in all of them.
Now check this same page in Macintosh and there too, although I have used different fonts for embedding, you can see it working flawlessly. (Use Safari or Firefox 3).
I have tested Naskh and Nastaleeq style Arabic script fonts in Windows and when the same page is accessed in Macintosh, Naskh fonts are used for display but again these are not resident on user's OS.
Any feedback and discussion is welcome.