HardMac.com has information about software that may possibly run MacOS 7, 8, or 9, under an Intel-based Mac. Originally the software was being developed to run under Linux or PowerPC based Macs, however it has been ported to Intel Macs. Note that the developers don’t have access to an Intel Mac just yet, however this looks promising.
The project is called SheepShaver, and it’s Open Source. On a PowerPC Mac, it runs the applications at native speeds, otherwise it emulates some of the hardware. It runs MacOS 7.5.2 thru MacOS 9.0.4.
Give this project a few months, and I wouldn’t be surprised to see something come out of it, that works. This would be important to those Mac-based genealogists who are using older software that runs under a Classic environment, and who want to upgrade to a new iMac or MacBook Pro.