ARM CEO Warren East hinted an ARM compatible version of the Windows 7 operating system may be on the way, and there are some other hints that Microsoft may be working on this:
And the launch of Windows 7 might make a convenient point for Microsoft to announce support for ARM processors. But obviously Intel might be trying to pressure Microsoft to delay such an announcement for as long as possible.
At present the "Release Candidate of Windows 7 does not mention ARM processors as part of the systems requirements, which remain restricted to Intel processors. But Microsoft does say in its press release "Windows 7 will work on a broader array of hardware than any other release of Windows at launch."