What's really interesting about the LG ST600 is that it's being sold as an upgrade to an existing TV, rather than as a standalone device.  Attaching the ST600 to your TV will give you full access to LG's internet suite of content and programs.
The one thing that's unclear from the initial information on the device is whether it's LG specific or not.  From the sound of things, the ST600 will allow users of any HDTV to connect to LG's service.

The ST600 is due out in the spring of 2011 with a price yet to be announced.