I just received an email from National Instruments about their new CAN interface for the Compact RIO system, the NI-9862 module.
You can read about it
here.
Now, I'm not sure how likely the NI-9862 will be coming to the FIRST control system, but it's promising.
It would be great to get rid of the funky conversion stuff we're doing right now. Having this module will take out some complexity in the system.