Intel released three new quad-core processors at CES 2007. This includes the Intel Core 2 Quad Q6600 processor which is clocked at 2.4GHz, with a price tag of $851. This is a bit cheaper than Intel's first quad-core processor but it's still priced way too high to become mainstream.
Cheaper quad-core desktop processors will follow later this year.
There's also the quad-core Intel Xeon X3220, clocked at 2.4GHz, and the Xeon X3210, which is clocked at 2.13GHz. These Xeon processors have a 1066MHz FSB and 8MB L2 cache and they cost $851 and $690, respectively.