What operating system do the iPad models use? Does it support multitasking?

The current iPad 3rd Gen models -- the iPad 3rd Gen (Wi-Fi Only), iPad 3rd Gen (Wi-Fi/4G LTE AT&T/GPS), and iPad 3rd Gen (Wi-Fi/4G LTE Verizon/GPS) -- ship with iOS 5.1, which supports multitasking.

The iPad 2 models -- the iPad 2 (Wi-Fi), iPad 2 (Wi-Fi/GSM/A-GPS), iPad 2 (Wi-Fi/CDMA/A-GPS) -- shipped with iOS 4.3, which also supports multitasking and can be upgraded to iOS 5.1 at no cost.

The original Wi-Fi-equipped and Wi-Fi/3G/GPS-equipped iPad models first shipped with iPhone OS 3.2 (Build Number 7B367). This version of the operating system does not support true system-wide multitasking, and instead only supports Apple's own Mail e-mail, Safari web browser, and iPod media applications running concurrently with other applications. However, the original iPad models do support multitasking when upgraded to iOS 4 or later.

"Power users" no doubt are pleased that the iPad models now have system-wide multitasking.

Will operating system updates for the iPad be free like the iPhone or will they cost money like the iPod touch?

As first spotted by MacRumors in the original iPad licensing agreement, the next major version of the operating system (4.x) would be provided free of charge [and it was].

Based on this information, EveryiPad.com originally speculated that subsequent versions of the operating system (5.x) presumably would require an upgrade fee, although the site noted that "only time will tell." In a nice surprise, Apple released iOS 5 at no charge for those using earlier iPad models.

Apple also notes that operating system "updates and releases may not necessarily include all of the new software features that Apple releases for newer iPad models."

Can applications that run on the iPhone and iPod touch run on the iPad models? Can the iPad models run Mac OS X applications?

Applications that can run on the iPhone and iPod touch models -- with the exception of applications that require hardware capabilities that the iPad models lack (such as a "phone" for any iPad or a camera for the original iPad models) -- can run on the iPad either at actual size centered in the middle of the larger iPad screen or "doubled" (which "blows up" each pixel in the iPhone/iPod touch application to twice its size).

The iPad cannot run Mac OS X applications. Those interested in running Mac OS X on a tablet might be interested in the Axiotron ModBook.

Also see: How does the iPad compare to the Axiotron ModBook? Which one is best for my needs?

Can the iPad run Linux?

Yes. As widely anticipated upon the release of the original iPad, hardworking hackers have managed to run Linux on a "jailbroken" iPad. This hack definitely is not necessary -- or even desirable -- for most users, but for the hacker community, running Linux on anything is a regular rite of passage.