Rui CarmoSony's LocationFree TV is a simple tuner/streaming media server using dedicated hardware and what seems to be a proprietary protocol atop port 5021.
Resources:
- ChangeIP's configuration page - for accessing home boxes via their dynamic DNS service.
- GPL Source Code for at least a portion of the software (turns out it's LiveMedia, and that it includes Mac OS X and Linux presets for compiling...)
- Engadget on the LF-W1HD, an HD version that uses MPEG-4 AVC/H.264.