At a time when laptop is in an identity crisis, Apple is hitching its wagon to the refreshed MacBook Air. Rumor mills say a new version of the light-weight notebook will come equipped with the Mac OS X, or Lion, Intel's Sandy Bridge processor and Thunderbolt fast connection interface.

By beefing up its ultra thin notebook, which has sold millions of units, Apple cold be pre-empting a threat posed by the likes of Intel's upcoming 'Ultrabook' which seek to build a bridge between the laptop and the tablet.

Meanwhile, the delivery of MacBook Air has dried up, in further evidence for Apple's plan to raise the notebook market benchmark by drastically refreshing the MacBook Air.

AppleInsider reported on Monday that MacBook Air notebooks are listed as Not Available for Shipping by Best Buy, although the laptop is still available in its brick-and-mortar retail stores. The report says all MacBook Air models on Apple's Online Store are ready for shipping.

According to reports, Apple is biding time to give final touches to Lion, and would release the updated MacBook Air notebooks only after the latest software update is ready. The Mac OS X is due for release in July.

Apple's Chinese manufacturing partners are ready to ship MacBook Air hardware, but Apple would rather have the new version of its ultra thin notebook have latest of Mac OS X, which will be the eighth upgrade of its desktop and server operating system for Macintosh computers.

Along with news on the refreshed MacBook Air, it's also reported that Apple has asked Asian manufacturers to ramp up production of MacBook parts as the company sees increased sales volume in the rest of the year.

Apple has asked manufacturers to shift gears as it hopes to take deliveries of more than eight million MacBook Airs in the third quarter, according to a DigiTimes report. This will be double the volume delivered in the second quarter.

The report also says Apple foresees the sale of as many 15 million MacBook Air units in 2011, up from 13 million forecast earlier.