Sling.com online video portal is open to the (US) public
If you don't have a Slingbox, right now Sling.com is just another online video site that has an assortment of TV shows and movies from Fox, NBC, CBS, Sony, MGM, and web content providers like College Humor. Honestly, you can find most, but not all of the same content at Hulu.
Sling does plan to upgade its software so that Mac using Slingbox owners can also stream live TV. But right now anybody with a Flash enabled web browser running Windows, Mac, Linux or something else altogether can watch the web video streams from Sling Media's content partners - provided you're in the US. The content won't play outside of the region.