I guess there are not many developers using 64bit, not Windows 64bit at least.
I think it's still a bit too early for a transition to 64bits; on Linux at least you can compile yourself most of the applications using 64bit or find them already compiled, but for Windows I would hardly find a 64bit version for half of the programs I use.
Anyway I've heard there were some problems using GDB on 64bit Windows, and it's nice to know it's working

.
Regards, XayC