My vote is for How much speedup does a hyper thread give? (in theory).
I have always been interested in how much preformance hyper threading actually gives. In fact I often turn off hyper threading since increases the cache that is available for single threaded applications. It seems like Konrad has done alot of testing with hyper-threading and is very knowledgeable on the subject. Possibly we can talk to him about elaborating further on the subject or at the very least do some tests to see how hyper threading affects things your average user does (Photoshop, games etc..). Either way in it's current state the information within the answers is excellent.
