You can search (he's searching for Wii Fit), add stuff to your watch list, or even bid for new items. The standard iPhone animations are there, sliding left and right whenever you access an item. There's even a photo view with a touch strip that you can browse through pictures belonging to auctions.
Next up is eBay and their own native application for the iPhone. Ken Sun. Their app is called "Auctions". The iPhone is already becoming the most popular way to access their auctions from a mobile phone, but a native app looks fast and more customized for the screen than Safari.