Half Life 3 Confirmed!

[D.B.Cooper]

What is the status of Half Life 3/Half Life 2 Episode 3?

The number 3 must not be said

Is Valve still working on any fully-fledged single player games?

Yes

An unidentified anonymous source at Valve has said that Half Life 3 has been cancelled. Is that source legitimate?

I personally believe all unidentified anonymous sources on the Internet.

http://www.guru3d.com/news-story/valve-is-working-on-a-new-single-player-game.html