Here is some concrete info that was just released.
Sonova (Advanced Bionics) Investor Presentation April 2013 | cochlear implant HELP
Also, if you look at the comparison chart on the same website and scroll to the bottom to the "Rumors" field, you'll find this:
http://cochlearimplanthelp.files.wordpress.com/2012/03/ciap-2011-phantom.pdf
When you consider that all implants have low frequency limitations due to the limit on the depth an electrode can be inserted, this is great stuff! However, don't be alarmed by the current lack. The harmonics of lower frequencies are still heard which the brain then figures out to perceive as bass. Most users are unaware of any lower frequency limitation once they settle in to their programming. Such a strategy would provide richer bass experience which adds to the overall quality of sound.