Theres been some rumours floating around recently about a residing "reverse hyperthreading" feature waiting to be unleashed on AMD's latest AM2 based dual core CPUs (whereby the power of two cores are harnessed as a highly powerful single core for superior performance in single threaded applications).
Turns out it was all rubbish according to The Inquirer :/
APOLOGIES to the fanbois, but I am about to kill some nice AMD dreams. Reverse Hyperthreading does not exist. It's one of the bigger loads of bluff and bluster cooked up in a long time.
AMD doesn't have any such technology. It would like to have it but even the upcoming K8L quad core won't be able to present a dual or quad core as a single core to the Operating system.