Twitter has released their official iPad application (in fact the same one as before, just updated with iPad support and some new UI features).
The current version is 3.1 and beside just being able to read/send tweets it also integrates photos, videos and webpages, depending of the content referred by a certain tweet which is particularly helpful and is made possible by the larger screen available. You can see the referred content by taping on a tweet and a panel will open on the right displaying the content. You can use gestures to reply, re-tweet, etc. Even if you don’t have a Twitter account, you can get content from some popular ones that Twitter put together and you’ll be able to read the latest news in various categories or sample media around the Web.
The application is free and there is no reason not to download it right away.