Maybe I'll be lucky and one of the Apple folks on here (Dan?) will read this. The release of Leopard seems to me to have broken support for type 1 fonts with custom tables, for example and most notably 'Expert' fonts (you know, how we got optical small caps and old-style figures before OpenType ...)
Symptom-wise, it's pretty much what happened with 10.3.5, which was fixed in 10.3.6, so I'm holding out for another cure. Hopes of that arriving with 10.5.2 weren't fulfilled. I don't know if this is in hand (I filed a bug report, but it was a bit sketchy) or not, but some fix some time not too far down the line would be much appreciated ...