Apple's new line of ultra-thin and ultra-light 11-inch and 13-inch MacBook Airs have been finally released and Apple fans are already all over it.

The new MacBook Air features the return of the backlit keyboard, a minimum 128 GB solid state drive (64GB for 11-inch models), powerful graphic chips, 4GB RAM (except the base 11 model), Thunderbolt I/O data port, Intel's ultra-low voltage Sandy Bridge Core i5 and i7 processors and runs on the new Mac OS X Lion.

While the Thunderbolt port allows users to connect various devices like a display or external drives, and helps move data 20 times faster than USB or 12 times faster than FireWire 800, the updated processor and use of SSD lets the new line of MacBook Airs run 2.5x faster than previous models.

And there's more good news - According to the experts at iFixit, the new MacBook Airs have SSDs that are user replaceable as they have not been soldered to the motherboard. This is good news because MacBook Air users can get to try out the next generation SSDs that promise sustained data rates in excess of 500MB/sec.

However, the RAM's still not user-replaceable and so if you're going to need more RAM, it's best to go with a 4GB model at the beginning.

According to PCWorld, the new MacBook Air will be the go-to device for executives and professionals and trade publication DigiTimes reports that shipments of the latest MacBook Air from the supply chain have already topped half a million units in June and the volume is expected to remain strong throughout July and August. Going by the figures, the series sales could top 14 million units this year.

MacBook Airs have been priced $999 (11-inch models) and $1299 (13-inch models) upwards.