Are mysterious MacBook Air shortages signaling a refresh?

It looks like it’s time for a new Macbook Air model.

Reports are trickling in that Best Buy and Amazon are suddenly scaling back their MacBook Air shipments. For those not adept at reading Apple’s tea leaves, this typically means a model refresh is on the way.

The big box retailer tipped its hand late Sunday when its web site changed the MacBook Air’s status to “Not Available for Shipping.”

Best Buy usually tries to forecast when out-of-stock products will resume shipping, but the availability of Air isn’t listed anywhere on the retailer’s site. Amazon has reflected a similar pinch in its MacBook Air supply, making a new product announcement look all but inevitable.

This isn’t the first time Best Buy has telegraphed a product release with its inventory system. But even with the retailer taken out of the equation, most of the industry agrees that the timing makes sense.

For months, speculation about Apple refreshing its darkhorse notebook has simmered as the company readies for the OSX Lion update. Earlier this month Apple threw the tarp off Lion at WWDC quoting a July release date, effectively setting the stage for a product refresh in the coming weeks.

Though the speculation surrounding the Air isn’t as active as the iPhone rumor mill, the notebook is still reportedly due for a hefty upgrade. Reports of a switch to Intel’s Sandy Bridge processor would add much-needed horsepower to the slender Air, and rumors of a new Thunderbolt port would nudge the notebook even closer to the flagship MacBook Pro.

Such a move is nothing to sniff at either. Apple moved 3.76 million Macs last quarter alone (up 28 percent year-over-year), and the market is already betting that an upgraded Air will spur unprecedented demand.