it has been suggested but i am not sure the dev that makes the windows release has successfully built a 64 bit release yet, and if there are any bugs in the build that would keep it from happening. dont worry it is somewhere on the todo list of that dev.
EDIT:
also there has to be a 64 bit linux release as the 32 bit release will not easily run on a 64 bit os, unlike windows where the 32 bit can out of the box run on a 64 bit os.