www.playdevil.com has an informative Q&A with the Producer, Romain de Waubert de Genlis (now that's a name!) and game Director, Raphael Colantonio from Arkane Studios.
They've asked eleven, rather pertinent questions and I think they've provoked a substantial amount of brain fodder from the interviewees. Certainly, before reading this DMoM&M was cowering in the shadow of HOMMV for me - now my curiosity is piqued.

Some further detail is given on the use of Valve's Source Engine, the expansion of the 1st person concept as well as RPG elements of the game regarding character development and choice of gameplay.

The RPG/action genres have combined succesfully before - if Arkane Studios, with their previous RPG experience, can take full advantage of the collaboration with Valve (apparently they're getting quite pally), perhaps we'll have a finished product of Thief III's ilk to play with?

For those of you who missed the interview first time round (it was taken off for a while), it's now back online