I know about AMD using 6 core phenoms, locking 2 cores and selling it as a 960T...
But since Hyper-Threading is an intel only piece of technology, unless intel have started buying Intels, locking cores/clocks and rebranding with different sockets, I dont think thats right
There is absolutely no hyper threading on that chip, and there is no way to unlock another two cores as the 955 is a true quad. Only quads with a T for (thuban) have an extra 2 cores.