i'm not exactly a Microsoft fan, but i do give them credit for sucessfully stealing most of apples os X GUI.... HA HA. Seriously, i smell a lawsuit in the works against Microsoft. It'sgoinig to be daghview (i know i spelt it rong)all over again.
Hmm.. does the most recent Windows 2003 and/or the prototype Vista or even further away prototypes have a GUI much different from XP? I admit I haven't seen much of OSX, but the type of GUIs we have today have been around for a while and previous more obvious lawsuits from Apple have failed, so I can't see why another one would be more successful.
Besides, Apple should've been sued by Xerox in the 80'ties, because it was from Palo Alto that Steve Jobs "borrowed" most of the ideas to Macintosh first graphical environment.
Server 2003 and Long Horn look like 9x. Vista has a thing called Aero and can run in a mode called Aero Glass that vagely resembles the OS X Aqua. They really don't look too much like each other. Just Google image search Aero Glass and you will get real screen shots of Vista and what it looks like. Intresting side note is that Darwin, the UNIX core of OS X can be downloaded for free. Its hard to find but Apple them selves let you have it. You just can't have Aqua. so OS X is free, just no GUI. Which is no big deal since you can make KDE look like Aqua. It is avaible in x86 and PPC. If anyone is intrested in it, I'll track down the website and post it's link.