I find it really unprecedented for an "awaited" PC game to remain hidden from public. As far as I can tell, first signs of development go all the way back to '07, although it may have stayed in the "on paper" stage for a long time. Even if so, I believe developers have been reassigned around 2.5 (?) years ago, so by then there must have been a pretty clear concept at the very least.
Pretty much only thing I could ever find was this youtube channel who supposedly uploaded two Titan videos - http://www.youtube.com/watch?v=E8bqbgCusdA and http://www.youtube.com/watch?v=ElKIg-tGY6g&feature=plcp, which are likely a fake or I just missunderstood.
Is Blizzard trying to avoid hype? Why? Do they want to overwhelm people with info at some point? Are they trying to go for the impulsive buyers?
Who knows, Titan could be a codename for a hoax