Tweak Tweak Twitter
The site's layout is now split-screen (much like in Twitter's official iPad app) with a smorgasbord of site features available in the right pane and your stream on the left. Basic navigation has mostly moved from the right side of the screen to the top, and keyboard shortcuts and unlimited scrolling have been added for your tweet-reading convenience. The biggest news is inline image and video support, with all major Twitter pic sites (plus heavy-hitting video sites like YouTube and UStream) supported.
This is all in keeping with Twitter's new "we're not a social network" philosophy, putting the focus on reading and viewing the site as real-time news, and aiming to be as viewer-friendly as possible for people who don't have Twitter accounts.