Roku

http://www.rokulabs.com/products/features.php#platform

"Open Platform: The Roku HD1000 is based on the Roku OS. An open platform that includes Roku’s advanced media APIs and the Linux Kernel. Using the Roku OS, developers can quickly craft innovative and custom applications for the Roku HD1000 that take advantage of our TV-centric user interface elements, network and memory card access, MP3, MPEG, windowing system, graphics library, and other media engines. In addition to the option to write C or C++ code with our SDK, custom installers can completely control the HD1000 without the SDK by using simple ASCII control commands over the serial or Ethernet ports. (C/C++ SDK available by the end of the year.)"