RC1 as well as IE 8 beta were a pain here when tried out. The beta for Vista's SP2 is supposed to be in a prebeta form to see a beta version soon enough. The build your friend reports having now is likely a prebata build still more or less using Vista themes until another development has that section of 7 ready for compilation.
As mentioned earlier on another Windows 7 thread someone started MS is likely pushing up the time table a little since many look at Vista as being an ME II flop due to the new version's design around newer hardwares. If a new version had come out inbetween instead of the simply long delay seen with Vista that would likely have seen a 256mb minimum with XP's 64mb 128mb recommended and Vista now seeing 512mb.
The explanation from an MS beta tester is that Windows is divided into several sections in the early stages finally being compiled into the first beta when ready for release. You won't see much new at this time and shouldn't expect to.
