Multitasking is one of the headline features of iOS 4.2 for the iPad. It’s definitely my favorite new feature and the one I know will get the most use out of day in and day out. So I’ll be seeing a lot of the Multitasking Bar, which is what gets pulled up when you double-tap the Home button in iOS 4.2.
The Multitasking Bar is where you go to switch rapidly between backgrounded or recently run apps. It also has a couple of extra items over to the its far left when you swipe all the way in that direction. There’s a button for toggling orientation lock on/off, minimal iPod music controls, and most interestingly, a brightness control slider.
The brightness control is a very nice addition, but it also brings to mind a huge miss / wish list item. If they can make room for the brightness slider, why oh why can we not have a toggle for cellular services (on the iPad 3G), and some other key services?

Oh man i am dying for that brightness slider! The iPad screen is just too painfully bright sometimes.
They should also make a screenshot style shortcut for brightness: home+volume up/down (or power instead of home). This wouldn’t interfere with any other actions and i think people who knew it would use it a LOT. I often find myself wanting to alter brightness when switching between apps, to me it’s almost as important as having hardware volume controls.