I haven't heard anything about when Adobe may release a 64-bit version of CS.
But what I can tell you is that any 64-bit software running on Leopard on a computer with a 64-bit processor will run significantly faster than 32-bit.
For those who own a 64-bit Xeon Mac Pro running Leopard, a 64-bit version of Creative Suite would offer a significant speed improvements. Where it would be most noticeable is in the length of time it would take to perform complex filters on extremely high resolution images.
Steve Jobs demonstrated this at the WWDC in 2006 using an image filtering test program. Both the 32-bit and 64-bit versions were run side-by-side, and the 64-bit finished running the filter in less than half the time it took the 32-bit version.
But for those running 32-bit processors, 64-bit software will make little difference.