Just had a look on Pixoligics site and it looks like there intel only as theres no mention of PPC's in the system requirements.

I kind of get a feeling that PPC macs are getting pushed out of the loop, it sounds awful but I wouldn't be surprised if support for them drops off considerably when the 3 year warrantys run out on the last bought PPC's and if the new version of OSX dosent support them as developers would concentrate on the new OS and X86 rarther than older technology, which I think they would as its just progression.

I also would watch out for any older softwares that you may have with leopard as its not completly unfalable with software, there were quite a few if I remember rightly that would not run correctly on it, one of the major ones was the Adobe CS2 suite, good job that CS3 was out but a pain for anyone with CS2.