Cable's solution to this is middleware software originally called OpenCable Application Platform ( OCAP) and more recently renamed to simply: OpenCable.
OpenCable Application Platform (OCAP) would allow the cable company to download the same software to every CableCARD 2.0 host device regardless of the manufacturer.
While it's difficult to really get a handle on what is holding up the works, it seems like the requirement for OCAP support is the biggest point of contention.
It would be possible for someone like TiVo to develop OCAP software like they are for Comcast right now, but it would be up to each provider to distribute the software to the box you rented or purchased.
With its middleware Biddle software (based on the same DVB-GEM spec as OCAP, and also available to cable operators) included on a Blu-ray disc, the company claims its ready to deliver an "interactive TV service" consisting of VOD, web browsing, e-mail, social networking access or nearly anything else you can imagine.