Anandtech is reporting on the changes that Socket AM2 will have. It was already clear the new CPU would require DDR2 memory, but it appears AMD is also using this architecture change to upgrade the current mounting scheme for Athlon 64 heatsink/fans. The new design is certainly very secure - more stable than the current design - but there are very few existing heatsink/fans that will work on the new cage. From Socket 754, 940, and 939 the same heatsinks have all worked on all Athlon 64 sockets. With AM2 that compatibility basically ends. I'm sure that both those who plan to upgrade to AM2 immediately and those who are going to wait (or even pass perhaps), will still be interested in this article.
