It's 32 bit.
Thank you Sagar.
Does that bother you? If it does, may I ask why?
Dov posted a lengthy response yesterday over in the dark UI thread in ID Feature Requests that goes into some detail about why ID is still 32 bit and when we might expect to see it change.
I think that you can reasonably assume a 64-bit future for InDesign, but not as an InDesign 8 (CS6) update. For MacOS, transition to Cocoa from Carbon was necessary for this to occur.
Note that there are in fact limited benefits of 64-bit over 32-bit. In general performance with 64-bit is not necessarily better than with 32-bit. There are cases where 64-bit performance actually can lag a bit behind that of 32-bit. The real benefit of 64-bit is the ability to have larger address spaces, thus eliminating problems that can occur with very large, very graphically complex documents when InDesign and its component graphics libraries run out of address space for content, work areas, etc. and either the program fails or has to spill out into work files.