Since the creation of CableCARD its inventor, Cablelabs, has been extremely stringent about how the standard was used. While CableCARD always has promise as a method for decrypting cable television on a PC, Cablelabs would not allow CableCARD to be used on computers they did not specifically approve. As with most things in the open-format world of the PC, Cablelab's tight clamp on usage meant that CableCARD never picked up steam.
However, Microsoft has somehow made a deal with Cablelabs to let go of that restriction. Cablelabs will instead allow CableCARD to function on any computer which meets certain requirements. Those requirements will be checked by a CableCARD compatibility tool that will be developed by Microsoft. In addition, CableCARDs for PCs will be able to use the Copy Freely flag, a DRM flag which was not previously enabled, thus disallowing users to copy programs decrypted by CableCARD.
What this means is that it should soon be possible to rent and/or buy CableCARD products which can be placed inside a TV and used to record encrypted digital television. This is significant, as it was until now unclear how HTPC users would be able to record cable television as unencrypted sources continue to disappear.