Apparently Quad cores are being released later this year -
"So, Intel has just launched its new dual-core processors based on the Core microarchitecture, and they are set to be replaced by quad-core processors at the end of this year. This announcement will make Intel's Core 2 Duo processors obsolete before they've even had the chance to really penetrate the market in any substantial volumes."
http://www.bit-tech.net/columns/2006...ng_soon/1.html
of course the author goes on to write
". . . in the long run, those cores are going to get used - it's not taken long for developers to develop multithreaded code for dual core processors, so I don't think it will be much more than 12 months before we see massively-multithreaded applications on the market."