Reports that Apple would release the new version of its ultra-thin MacBook Air laptop this week are wrong, says John Paczkowski at All Things Digital. The new MacBook Air model is actually coming next week, according to “several sources” who spoke with Paczkowski.

Rumors about the imminent release of new MacBook Airs have been floating around for some time. At the end of June, Best Buy halted all shipments of MacBook Air orders, listing the product as “not available.” This, of course, set the rumor mill into motion. Then, last week, we heard that an update would come on July 13. But here we are, two days later, and still no new MacBook Air.

In addition to release date murmurs, we also hear that the new MacBook Air line will receive some major spec upgrades. AppleInsider reports that the 11.6-inch and 13.3-inch models will now come with 4GB of RAM, up from the 2GB offered in the last iteration.

That information comes via Concord Securities analyst Ming-Chi Kuo, who also reports that Apple will do away with the 64GB SSD storage option, and replace it with a minimum size of 128GB. A 256GB option will also be available, Kuo says.

On top of this, the new MacBook Air will likely include Intel’s Sandy Bridge processors, which are perfectly suited for the laptop’s thin design. MacBook Airs will also likely sport Apple’s super-fast Thunderbolt data-transfer system, as well as possible backlit keyboards.

While there has also been much speculation about the possible release of Apple’s new operating system, OS X Lion, it appears unlikely that will happen next week, as the company is still working out a few minor glitches with the system. But you never know — Apple has pulled off unlikely releases before.