The TouchPad uses the Exhibition mode introduced in September 2010's WebOS 2.0 whenever the lock screen is engaged. Exhibition mode comes on when the device autolocks or when you press the power button, and you can set it to display the time, your calendar, a slideshow of photos, or any third-party Exhibition services you have installed. Note that you can't get out of Exhibition mode until you remove the TouchPad from the optional charging dock or press the tablet's Home button; gestures are oddly ignored. When in Exhibition mode, the TouchPad screen doesn't turn off, an energy waster at odds with HP's green tech efforts -- and a battery drain when not connected to wall power. There should be a way to set a set a screen-off sleep time when in that mode. (You can manually turn off the screen by pressing the power button, but I found that the screen would reawaken in the middle of the night.)
One area where the TouchPad differentiates itself is its ability to pair with a WebOS smartphone over Bluetooth and, thus, use the TouchPad as the phone for voice or video calling via the Phone & Video Calls app. Apple has the FaceTime app on the iPad 2 for video calling (via Wi-Fi connections only), and it too can use Skype and other communications apps. But the advantage of HP's approach is that it lets you use the Wi-Fi-only TouchPad for such communications even when you don't have a nearby Wi-Fi connection.
Given the (initial) paucity of TouchPad apps, it's hard to judge the overall quality of WebOS apps, to see whether they're as rough as the majority of Android apps or more polished apps as tend to exist for iOS. The Facebook app, for example, is nicely done on the TouchPad, but the Kindle app's text is malformed at all but the largest sizes, so reading books is an unpleasant experience. USA Today has a terrible design compared to its iPad version, but that's the fault of creator Gannett, not the TouchPad.
I have to say I'm disappointed by the underwhelming nature of most of the TouchPad's included apps. The key OS innovations were developed for WebOS 2.0; in the intervening nine months, there should have been time to really polish those apps and make them at least as feature-rich as their counterparts in iOS.
The bottom line is, at least in these early days of the TouchPad, you won't be using it to run apps as you would an iPad or, increasingly, an Android tablet.
App stores and app installation. There are tens of thousands of apps for the iPad 2's iOS, from games to scientific visualization tools. Sure, there's a lot of junk, but you'll find many useful apps as well. As previously noted, there are just a few dozen TouchPad apps available, few of which are more than toys.