This internal PCI express card made by Cetoncorp can record 4 channels of cable programming at one time including premium channels. It is currently only available for Windows. Any interest in getting this to work in XBMC?
Take a look.
http://www.cetoncorp.com/buy.php
The world’s first multi-tuner PC card for digital cable
The Ceton InfiniTV 4 is the world's first multi-tuner PC card for watching digital cable TV on the PC, including support for premium cable channels. It enables Media Center PCs to play or record up to four live channels of HDTV at once, and stream live HD channels or recordings to multiple HDTVs throughout the home, all from a single cable connection and a single CableCARD™.
Replace your cable set-top boxes and their costly monthly rental fees and enjoy premium cable TV throughout the home, all from a single PC. With the Ceton InfiniTV 4 your Media Center PC becomes a complete entertainment platform for all your media, including premium cable TV.
Four Live HD Channels At Once
Watch and/or record four live channels of standard-definition or high-definition TV simultaneously, including all your favorite premium and encrypted cable channels. * Four, dual ATSC/QAM 64/256 tuners
* CableCARD M-Card DRM Processor
* Open Cable Unidirectional Receiver Specification - OC-SP-OCUR-I08-081114
* Digital Receiver Interface Specification - OC-SP-DRI-I03-090206
* CableCARD Copy Protection 2.0 Specification - OC-SP-CCCP2.0-I10-090904
* CableCARD Interface 2.0 Specification - OC-SP-CCIF2.0-I20-091211
* Digital Cable Network Interface Standard - ANSI/SCTE 40 2004
Requirements
* Microsoft Windows 7 Home Premium, Windows 7 Professional, Windows 7 Enterprise, or Windows 7 Ultimate
* 2.0 GHz or faster CPU minimum, either 32 bit (x86) or 64 bit (x64) – 2.7 GHz or faster dual-core CPU is recommended
* 2 GB of RAM minimum – 3 GB or more is recommended
* 1 PCIe slot, which can be either an x1, x4, x8, or x16 type slot
* HDCP compliant on-board graphics or graphics card
* HDMI out, or DVI out with separate audio out
* Multi-Stream CableCARD™ (M-Card) – available from your local cable provider
* Digital cable subscription from a U.S. cable provider