With today's announcement of the iPad, we heard about a new SDK for developing apps. We also heard, though, that the iPad will be capable of running all current iPhone apps without modification, downloaded straight onto the tablet from a built-in App Store. Either you can run apps normal sized on the larger screen, or, using pixel-doubling, iPhone-native apps can run full screen on the iPad. Apple has already rewritten all of their own apps using the new SDK (which will be available for download today on Apple.com), and I'm sure we'll start seeing tablet-driven development from iPhone developers immediately. A few companies, including EA, Gameloft, and the New York Times, have already gotten a head start on iPad development and showed off a few apps in the event earlier today.
While graphics-based iPhone apps are probably going to look pretty decent on the tablet, text-based applications look a little awkward when it's just bigger text. Native apps are going to be a must to really make this platform work, and I'm looking forward to seeing what current (and new) developers do with the new screen size and format.