Currently Intel's quad-core processors aren't real native quad-core processors, they are just two dual-core processors slapped together. Initially AMD fired heavy critic at Intel because their chips aren't "real quad-cores" but most people simply don't care because the chips do their job pretty well.
Now the funny thing is that AMD is planning to do the same thing for their Montreal Opteron processors. The firm will use two of their upcoming 45nm quad-core Shanghai processors to create an eight-core Montreal processor.
This quad-core server processor is expected by mid-2008.