It couldn't be that hard to get Mobile Webkit to support embedded fonts, could it? Safari for the Desktop now supports embedded fonts, even opentype fonts (whereas it was recently limited to just .eot fonts).... as does other webkit browsers like Google Chrome. How tough can the transition be?
However, reading around, I found
this page, which suggested that the iPad might support embedded svg fonts. Has anyone tested this? I assume this page is referring to support for Safari mobile, but perhaps they'd work in iBooks too.