You'll need a SlingBox, OS X 10.4, and a Mac (Intel or PowerPC) to use this beta. What you can't use, though, is an Airport Express. As explained in the FAQ, since the SlingBox needs to be hardwired to your broadband source.
Since I don't have a SlingBox I can't offer up many screenshots, but there is one after the jump
Here's the not so exciting screenshot:
Here's hoping they will work on making the interface a little more Mac like before it leaves Beta.