Apple is offering laptop users streamlined back-up with its first wireless storage device, called Time Capsule.

The new appliance is essentially an AirPort Extreme wireless base station that contains a hard disk drive and works with Leopard's Time Machine back-up application. With the new hardware added to the software, users can now back up and restore data over a wireless network, instead of having to jack into a cabled external hard drive.

Apple said pre-ordered units of Time Capsule are already shipping. However, Apple's online store is showing a five- to seven-day shipping delay for new orders.

When CEO Steve Jobs introduced Time Capsule at Macworld in January, he said it would ship in February – and the company met Jobs' deadline with just a day to spare.