Thanks to Mackey D for pointing me in the direction of this article at Overclockers.com:

As we mentioned the other day, AMD appears to have come out with a new placement strategy for its processors. Essentially, AMD will make socket 939 their mainstream and better solution, and socket 754 their value solution. While it still looks like one socket too many, putting the two sockets into very different markets is acceptable and should reduce the confusion down to reasonable levels.