CNET has an article stating Adobe is dropping 32-bit support on the Mac platform with its release of CS6. If you read between the lines, this means only systems compatible for OS X Lion will be able to run CS6 though the article does not explicitly state that.
For Windows users, Adobe will be supporting 32-bit for Windows XP. However, in an interesting twist they are not supporting Windows Vista at all. You will need to upgrade to Windows 7 to get CS6 on 64-bit.