The SiliconDust HDHomeRun Prime is essentially the CableCard version of the HDHomeRun Dual, which I reviewed in early 2012. However, the latest software update makes it potentially more powerful, by making it capable of streaming cable to a DLNA device like the PlayStation 3.
While the HDHomeRun Prime could already stream to a number of devices, why pay for a second cable box when you can now use a PS3? The SiliconDust HDHomeRun Prime is designed to work with Windows Media Center and extenders like the Xbox 360, but the newest update will please people (like myself) who haven't yet invested in Microsoft's gaming ecosystem. There is also an iPad app as well.
The device is about the size of your hand and takes a CableCard, Ethernet, and a coaxial cable. It features three tuners, unlike the Dual's two, and can be used as a DVR on a PC.
If the performance of the Prime is anything like the Dual then you'll need a fairly robust network to get it to work: this means either in a house with no competing Wi-Fi signals, or using Ethernet connections where possible.