Rumors that we might see Half-Life 3 at the next E3 conference are apparently false.
Half-Life 3 has been heavily-anticipated by fans for so long that we're starting to get some serious Duke Nukem Forever vibes from the game. Not because we expect it to be terrible, but because we have no idea if the game will ever actually materialize. We can however say with certainty that it won't be appearing at E3 2014. Valve says so.
I can't confirm all too much since the development is still in early stages, but for now I can confirm that we are going to release on both current and next generation consoles and we will also release the game on our own platform exclusively for PC and Mac. We hope to have the first trailer ready for E3 2014.
That quote appeared on a games blog calling itself "No Shit Shurlock," and was attributed to long-time Valve developer John Guthrie. Guthrie's tenure with the company dates back to 1997, so you'd expect that if Half-Life 3 were imminent that Guthrie would know about it. Unfortunately for the blog that published those words, Valve has reviewed the article and claims that the whole thing is "bogus."
Normally we wouldn't report on something like this. The story here is effectively, "little-known blog publishes rumor, rumor is quickly countered by people who might actually know what they're talking about." That's not really enough interesting information to base a proper news story on, and as a result most outlets never reported on the original rumor. It has however, spread through social networking sites and forums, so we may as well help kill this idea before it takes root and riots break out at the next E3 over the lack of Gordon Freeman.
To reiterate: Half-Life 3 may or may not be in development, but there's almost no chance that you'll be playing it soon. We apologize for any bubbles that sentence may have burst.