The Windows Hardware Compatibility list (HCL) has been updated for Windows 7. So far there are no entries form the major hardware manufacturers, but I’m sure that will change within the next couple of weeks as they continue submitting their drivers for WHQL testing.
Note that you can also check the hardware manufacturers Windows 7 pages to find out if they will provide Windows 7 support for your device. HP for example has the Windows 7 Upgrade Option Program. All models that are eligible for Windows 7 are listed here (US site, select your country for other localized products).