Unfortunately, there aren't any PowerMac emulators yet. If you just need to run some older software, I can recommend Basilisk II at http://basilisk2.cjb.net . It will run up to MacOS 8.1 and any software that will run on a 68k software (as well as supporting ethernet, direct SCSI, and the like. I've burned CDs in it. And it's free!).
On the other hand, Microcode Solutions is fairly close to a PowerMac emulator, you can watch progress at http://www.microcode-solutions.com. It won't be free though :)
Feel free to drop me a line if you like, I've been messing with emulation for awhile now :)
Scott |