Silicondust HDHomeRun Prime
The HDHomeRun Prime, by Silicondust USA (a wholly owned subsidiary of Silicondust Engineering, New Zealand), is an external HDTV tuner for personal computers. It has three independent tuners, interfaces to the computer via ethernet, and supports a multi-stream CableCARD. Support for this device has been added as of the 0.24 release. Using this device, MythTV is able able to record any encrypted digital cable channels marked 'copy freely', making it comparable to firewire capture from a cable box. Note that some channels will be encrypted by PlayReady, and it is unlikely that MythTV will ever be able to decode those channels.
This device is not currently available for purchase.