While AMD has just recently launched their first 4x4 series of hardware, they are still seeming to lack behind in technology compared to Intel due to that when it comes to a single chip with four cores they have been beaten to market. They won't let it slide, though, and have recently, yet quietly, announced the released of a true quad core processor. Even truer than Intel's own solution. The first of these processors was demonstrated today, considerably later than their initial roadmap. While the information is sparse, AMD did try to play up the advantages they claim their solution will offer, dubbing Intel's quad core "inefficient":

AMD believes that Intel's approach to put two dice on a single slice of substrate to build a quad-core processor - like Intel Corp. did with its Intel Core 2 Quad/Extreme and Intel Xeon 5300-series processors is inefficient and AMD's "native quad-core" design will provide better performance and scalability for servers.
While AMD has shown efficiency to be one of their best fields so far, the Core 2 Duo has really set them back. Until they make some serious architectural changes, it may be difficult for them to compete with Core 2 and its variants. Luckily for them, the first planned quad core chips will be based off a 65nm design and rely on a more efficient method of putting four cores together, which make give them enough of an advantage to make up for the time lost.