Well, while browsing the latest EDGE magazine (it came out yesterday), I came across a recruitment ad by Eidos Montreal at the back of the mag:
(rubbish phone + shaky hands)
As you can see it says they will announce a new project on, well, the 11th of May. And those words you can't really see beneath it are:
Now the only game that's featured in all those is, yep, you guessed it, Thief:
Just to confirm it:
" A posting on Eidos Montreal's website suggests that Thief IV may be about to undergo development. The post states states that, "Eidos-Montréal is proud to announce the recruitment for our 2nd "AAA" project. ... A hint! The title begins with the letter " T "... The article then goes on to draw several other conclusions. Nothing is known yet on what a possible new plot might be, apart from claims that it was initially intended to be a "retelling" of the original games. "
I guess I'm looking forward to it....