Most of the work in porting Safari has already been done with the release of iTunes for Windows, I think. The music store (at least on a Mac) is rendered using Apple's Web Core, the underlying engine used by Safari, the new Help program, Sherlock, and the Mail program to display HTMl/web content. Since the Web Core is based on KHTML my guess is that it's also used in iTunes for Windows. All that's needed is a front end (which shouldn't be more than a 2 MB download).
Safari For Windows