http://imgur.com/a/FojoD#0
This isn't any kind of guarantee of Half-Life 3, but if they use every extension they are allowed to use, they have around 2.75 years to release something tangible.
I hope that, now that there's a ton of internet buzz about this, Valve will make some sort of an announcement soon, but it could still be a while before we know if this pans out.
Again, this is nothing more than a trademark, and I'm in no way saying HL3 is confirmed.
HALF-LIFE 3 TRADE-FIRMED....
Still. Seems to signal possible good news.
That said, we can all dream right?
/meanwhile at valve...
Gaben: "Hey so yeah we are like 10 years out on Half-life 3 so what do we have?"
Gaben Prime: "Well, we could put out a press release about Ricochet 2."
Gaben: "Nah, lets save that for December. How bout filing a trademark for Half-life 3?"
Gaben Prime: "Totally. RAISES FOR EVERYONE!"
I mean, I might have the tone, content, facts and everything wrong but its possible it went like that.
Wait hang on... Gaben and Gaben Prime? There's more than one? That explains a lot, actually.
Yeah, he was created when he went back in time after injecting the red matter into a Sun. It wasn't entirely supposed to happen, but he does offer advice to Gaben from time to time.