This processor is codenamed Clovertown and its basically two Woodcrests on an MCM. The release date isn't known but it will likely take another 12 months before you'll see this chip in stores.
Intel has been hell-bent on not losing out to AMD on any more milestone releases, and it is going to be the first to demo a four core CPU, even if it is a hack. AMD has shown four ways as early as last October behind very closed doors, but this will be the first public showing. So congrats Intel, you won this round.