I think there is some confusion here. CableCard tuners currently work via the USB bus. In fact, even the PCI internal cards plug into the motherboard USB header, and the tuners show up as a network device within Windows.
This is basically the same functionality that CableCard provides, although this proof of concept is slower than cablecard on channel changes. See the EngadgetHD post w/video. (I can't post links here because I don't have enough posts yet...but it was posted yesterday).
Additionally, CableCard was opened up to be available to use with all PCs, where in the past it was limited to a select few OEM models. And there are MOCUR multistream tuners that will support 2, 4, and possibly 6 tuners per cablecard. CableCard was also announced to support SDV (Switched Digital Video), which is spreading around to allow cable providers to add more channels by only sending the ones requested to your house instead of all of them all the time. This should make it easier for enthusiasts to get into media center, much as they would do with a TivoHD using cablecards. Anybody can plug in the tuner and use it either via a PC attached to the TV or via an extender like the Xbox 360.
DirectTV was also working with MS on a tuner, but they as well as Dish both put their projects on hold, even though both setups supposedly were working and the Dish project even had a beta program.
So the CableCard solution for all of us is official. The other two hopefully will make it out as well, but there have been no announcements other than the projects were put on hold. It is odd that Dish would come to CEDIA with this after announcing about a month ago they had stopped the project, so I'm hoping it will see release at some point.