I was just in this position. After pricing out a decent AM2 setup, I decided to just buy an FX-60. It should last me more than long enough to ride out the AM2 phase and hopefully jump into quad-core with DDR3.
Really, DDR2 prices are what killed the upgrade for me. And, let's be honest, there's really no AM2 offering (currently) that makes the extra hundreds of dollars worth it, IMHO. I bought the FX-60 and 1TB of storage for less than it would cost to 'upgrade' to a slower AM2 setup.