Intel has unveiled their quad core CPU meant for mainstream computing, the Q6600. Nothing real surprising here, it is pretty much what everyone expected. It is clocked at 2.4 GHz with a locked multiplier, so you overclockers will have to look elsewhere. It also contains dual 4 MB L2 caches and uses the current LGA775 package.
You will probably not see the performance gains you would hope for the mulitple cores. Programs are just not written to exploit the multi threads needed to fully utilize it. As the tools and coding get better that may change in the future, but for now the gains will be modest.