At long last, Eidos Montreal has finally announced Thief 4. Initially the announcement was made by Community Manager René Valen on the TTLG forums, but eventually the official site made space for the new game.
The main site for the game has no information whatsoever past a logo, and links to the official forum and twitter. The game is apparently in very early stages, hardly into production.
In the world of gaming, there are mainly three phases - the concept, pre-production, and production - and right now we’ve reached our goals with the conceptual base, the story.
It would be asking too much to expect that we will see anything more about the game for a long time, and indeed the game will not be shown at E3. For now all the fans have is the logo (which is tentative, Rene assures us) and sure enough the community has exhausted that avenue of anxiety.