After dual core and the revised Core 2 architectures, Intel's next big step to push performance will be their upcoming quad core CPUs. They have now made pricing available for these CPUs, which should be available within the next 4 months. They aren't cheap by any stretch of the word, starting at $851 for the Quad Q6600, and starting at nearly $1000 for the Extreme QX6700, and that is in quantity. As 2007 goes on, they should see a significant drop in price:

The sources suggested that prices of quad-core CPUs may start declining in the third quarter of 2007 when Intel is expected to launch its next-generation quad-core processors, codenamed Yorkfield. At the same timeframe, Advanced Micro Devices (AMD) will likely begin releasing its own quad-core CPUs, the sources said.
Even so, it will be hard for the quad core to catch on with that sort of price tag. AMD's 4x4 systems will likely be cheaper, at least in the short term. Intel is still beating AMD to the punch with quad core though, which gives them a first to market advantage.