According to this post on Engadget, and verified by SiliconDust and CableLabs, the SiliconDust HDHomerun Prime CableCARD tuner has passed CableLabs certification as of May 1st, 2011. What does this mean? Well for one we should see the HDHomerun Prime available for pre-order soon. Secondly, this means that there are now two Cable Labs certified Multi-Stream OCUR (OpenCable Unidirectional Receiver) devices available for HTPC enthusiasts. Unlike the Ceton InifitiTV 4 that can receive 4 streams from one Multi-Stream CableCARD, the HDHomerun Prime can only receive 3 streams from one Multi-Stream CableCARD. Like the Ceton InfiniTV4, however, the HDHomerun Prime will mostly benefit users of Microsoft Windows 7 Media Center, but ther HTPC programs such as SageTV can use M-OCUR devices DRM free as long as programs are flagged as "Copy Freely." Another advantage to the HDHomerun Prime is that it is a networked device like all other HDHomeruns before it.
SageTV can currently access the InfiniTV 4 tuner using a plug in by Andy VT (author of DVRMS Toolbox) called SageDCT.