Canon UK have a notice posted on their website concerning an issue that has been discovered which "...prevents the development of RAW files in DPP 3.11.10...". I'm not quite sure exactly what the nature of this issue is, since it is certainly possible to open 5D MkIII RAW files with DPP 3.11.10, adjust them and save the results to JPEG files. I have done this and many other people have too. I have seen comments that there may be some issues with the noise reduction algorithms not quite working in the same way that they do with RAW files from other cameras (especially at low NR settings), though they do certainly seem to work OK at higher settings. There's also a sharpness issue reported by some which can be worked around by going to the "General settings" tab of the "Preferences" menu selection and changing the setting from "High quality (recommended)" to "High speed".
The Canon Japan website contains the statement (machine translated!) "When the development process by using the "DPP ver3.11.10", the data were taken in RAW format "EOS 5D Mark III", become somewhat blurred image such focus", so I guess they are acknowledging a sharpness issue.
We did discuss some of these issues in the EOS forum here last month - see http://www.bobatkins.com/smf/index.php/topic,969.0.html
If I get more information I'll post it.
In the meantime, here is the full text of the Canon UK statement: