Win10 64 bit; 24 gigs RAM; third-gen i7 CPU; ATI 79xx GPU
Broken: hash a0c1876
Short description of error
When you enable the rendertime dicing in the subsurf modifier (for displacement) and the mesh has more than one material index, both the rendered view and F12 render will reveal that the faces are not connected in any way (but displacement without the dicing works as it should
Exact steps for others to reproduce the error
Open the .blend file and switch to the rendered view (or press F12)
I'm not entirely sure if you're accepting bug reports for this feature yet, but then again there's no user-visible list of remaining todo items so as to know whether to report something.