I just noticed that the Safari on my iPad with iOS 4.2.1 will display embedded .ttf/.otf fonts -- fonts that are not part of iOS but downloadable from a web page. For an example try my Egyptian Test Page.
This is a very important capability, since users are not able to add any fonts to iOS devices.
My iPod Touch, still on iOS 4.0, lacks this feature, so it must be new. Also the new WOFF format, designed to offer greater IP protection, does not work yet.