Windows
XP (32-bit), Vista (32- and 64-bit) & 2008 Server

AIX
5.2 & above

Solaris
10 & above on Sparc

HP-UX
11i v2 & above (Itanium)

 Mac OS X
10.5 & above (Intel Chip)
currently 3.0.2, 4.0 ships soon!

Linux
Kernel 2.4, 32 bit 
Kernel 2.6, 32 bit