From the (ex) Fusion 3 Beta forum:
http://communities.vmware.com/message/1534504
... Any news for this little problem?
Since then, I have made some more experiments, and the glitch still exists in Win7 x64 VMs, both in Fusion 3.1.1 and Parallels 6 (while in native Boot Camp 3.1 x64 it doesn't occur anymore).
Do others have the same problem?
My hardware is a mid-2009 MacBook Pro (9400M graphics) with a LED Cinema Display (and the colour problem is there both with and without the external display attached).
Of course, it's only an innocuous cosmetic glitch; but it would nevertheless be interesting to know what causes it (ASU and/or the virtualisation "environment"), and why it occurs only on x64...
P.S.: Another screenshot of the problem can be seen, for example, here:
http://www.simplehelp.net/2010/03/24/how-to-install-the-boot-camp-3-1-update
... i.e., with the ASU logo that looks like it is only with 256 colours, or something like that (both with and without Aero Glass enabled).