AMD will launch a number of Quad core Phenom processors this year and the top two will work at 2.8GHz. The 2.6GHz and slower clocked CPUs will be released in socket AM2+ only. These CPUs will be sampled and available by late 2007.
The 3GHz CPU will be delayed until 2008, but the sweet spot for both Intel and AMD is the 2.4GHz CPU, and this is where the money and volume sales will come from. This will probably ignite a new price war.
Obviously, in addition to 2.8GHz FX and 2.6GHz CPUs, the Phenom X4 will launch at 2.2 and 2.4GHz.