I'm guessing here that the htt you are referring to is intel's hyperthreading technology. In the AMD world htt refers to HyperTransport technology which is the way AMD cpu's communicate with the rest of the system. AMD cpu's don't support hyper threading.
Now this is just a guess but perhaps the MB supports hyper threading because A)its vary similar to their equivilant intel board and/or supported in BIOS (ie. not removed) or when the dual core a64's come out a similar (but probably much better) multi-threading implementation will be supported.