Apple's iPad has gone on sale in the US this weekend with Apple fans clamouring to be one of the first wave of people to own the new tablet computer that promises to change the way we interact with games, the internet and much more.

Apple stores opened across the country with hundreds venturing out over Easter weekend to own one, while thousands stayed at home waiting for the UPS man to show up at their door in a launch that went to schedule and without issues.

Although Apple has not yet provided details of opening-day sales that hasn't stopped Piper Jaffray analyst Gene Munster claiming that he believes between 600,000 and 700,000 units has been sold on the first day.

If that number is right, that contrasts massively with the 270,000 iPhones sold during that product's initial launch.

The number will no doubt please Apple as they have yet to put the 3G version on sale in the US or announce availability and pricing elsewhere on the globe, especially the UK.
However eagle eyed Apple fans have already noticed references to other iPhones, iPods and even iPads in the new device's operating system.

According to Boy Genius Report, the Apple iPad lists the following references in the iPad file system:

- iPhone3,2
- iPhone3,3
- iPod4,1
- iProd2,1

The first two, iPhones, the second is an iPod touch, and the last? A major revision to the Apple iPad supposedly.

The rumours tie in with earlier rumours that the iPhone will be getting a major OS overhaul later year with multitasking support being added, it would be logical that if that was to happen the iPad would also receive a similar update.