AMD plans to release four different quad core processors in the next couple of years, but details are still murky. In the second half of 2007, the company plans to release a quad-core server chip codenamed "Deerhound," which will have a shared L2 cache and will be manufactured in a 65nm process.
Next, in the first half of 2008 comes a desktop chip called "Greyhound," another four-core processor of unspecified clock speed that débuts HyperTransport 3. The second half of 2008 brings a server chip called "Zamora," which has a shared L3 cache, and around that same time comes a quad-core workstation chip AMD calls "Cadiz."
AMD Roadmap [HKEPC Hardware, via The Inquirer]