Timothy Prickett Morgan over at the Register Has a nice article on IBM doubling up processors to fit into a single socket. In some servers this may push the limits of the number of thread Linux can handle so expect patches to push this up further in the future. The article also has lots of other juicy details on the Power 7+.
I wish they would make one that I could drop in an athlon socket. I would rewrite my BIOS in a heart beat.