Are you really? Can you do the following command to be sure?

My understanding was that the changes for MHD were integrated into CSSU-T a while back, and are now the standard replacement for hildon-desktop. This is why standard desktop for CSSU-T can have 9 panes now. I'm pretty sure on has a counter-dependency on the other and simply uninstalls it silently if found during update (as long as no conflicts are found). And since the behavior is the same, it may have done that for you in the last update without you knowing or noticing it.

Regardless, the log makes it clear what's happening. Two packages are trying to use the same file, since the new hildon-desktop touches a file that didn't exist before unless you had MHD installed. There are only two viable solutions: Remove mhd and install hildon-desktop, or force-install hildon-desktop and let it take control. (The latter will probably bork your apt setup a bit though, and if you later try to remove mhd it will break hildon-desktop...)