Nintendo has posted a story on the Internet Channel over at wii.com, where Nintendo's Internet Channel people sit down to discuss the channel from their perspective.
You will notice that there are links that open a video player in various places. These videos show things like the new intro, new zooming capabilities (it has several levels of zoom), the new scrolling, and one shows that that the toolbar can now be (automatically) hidden. (Remember to left-click these links, since opening them in a new window doesn't work.)
There are new buttons on the browser toolbar too. You get direct access to searches, to open a new URL, and you can get information on the current page.
The startup time has also been cut considerably. It now starts up nearly instantaneously.
It also seems that Nintendo is strongly considering support for hardware keyboards. Let's keep our fingers crossed 🙂
Update: Replaced the Japanese link with a link to the English version.