Christina Warren from TUAW has an article at Download Squad on installing Windows 7 beta on a Mac:
Although Intel Macs can run Windows 7 in Boot Camp, for most users, the easiest and most hassle-free method will be to use virtualization. This way, you can test out all the features of Windows 7, without having to dual-boot. The big pitfall for virtualization: gaming and HD-video playback, are less an issue in Windows 7 because those areas are still being tweaked and aren’t ready for prime time anyway.