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

The iPad 2 models -- the iPad 2 (Wi-Fi), iPad 2 (Wi-Fi/GSM/A-GPS), iPad 2 (Wi-Fi/CDMA/A-GPS) -- ship with iOS 4.3, which supports multitasking.

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.

In a review of the original iPad, Engadget succinctly explained the downside to not having true system-wide multitasking on the iPad at that time:

[It] means that for things like IM apps, you're either having a conversation or you're not. For those of us who are used to the iPhone way of doing things, that's at least familiar, but if you're looking to have a conversation while getting your email in order (as you would on a laptop), you're out of luck. The same goes for those of us who like to keep a Twitter app open in the background to monitor updates. Even updating settings or downloading software is a chore due to the stop-start nature of the OS. You just have to go one. at. a. time. That's almost acceptable for a smartphone -- you don't expect laptop performance -- but this is different. Admittedly, there aren't a huge number of scenarios where you need to be multitasking, but it's not uncommon for Engadget editors to keep a running IRC session, AIM, a browser, Twitter app, Skype, and music player open at the same time, and we suspect a lot of you out there do the same (or similar).

"Power users" no doubt are pleased that the iPad models no longer have the limitation of no 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 iPad licensing agreement, the next major version of the operating system (4.x) would be provided free of charge [and it was].

Subsequent versions of the operating system (5.x) presumably will require an upgrade fee, although only time will tell. Apple also notes that "such 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. Although surprsingly, as of the date last updated (see top), no one seems to have made an effort to run Linux on the iPad.

It is typically assumed that hardworking hackers will run Linux on most devices, but perhaps interest in the iPad among Linux enthusiasts is lacking and the community has decided to instead focus on alternate tablet platforms. If you have more information about efforts to run Linux on the iPad, please share. Thank you.