AMD have not even stated that AM2 is going to bring massive improvements, that it is mearly a technology enbler for future CPUs.
Look at their roadmap, the CPU frequency and ratings ratios are staying the same. There current roadmap even shows the 5400+ being the fastest non FX processor into 2008.
However I bet the roadmap will change, when AM2 is finally released, but for the time being they are keeping overly quiet.
They must have being some development in the last three years since AMD64 was released, there havn't been that many changes,
i.e. dual core (designed from the start to be dual core capable), frequency (more down to manufacturing) and a few minor MC tweaks.
With 65nm coming online soon plus the other manufacturig deals, I bet prices will come down quite radically, they may well forgo the highend,
but keep a very good position in the low to medium performance sectors,
until most desktop software is truley multi threaded, then they'll be able to bring the opteron technology to the desktop, i.e. quad core, (Z-RAM maybe),