In a response to a question posed by a fan, Gabe Newell, founder and CEO of Valve Software, stated the company wouldnt be making any announcements at E3 next month. Newells exact response was as follows:
We are not announcing anything at E3. Really. We are not announcing Half-Life 3 or Portal 3 or Left 4 Dead 3. We are going to be showing stuff everyone already knows about (CS:Go, Dota 2, 10" UI, ...)
The e-mail conversation was posted on ValveTime (formerly known as Half-Life2.net), which also received further confirmation from Newell that the e-mail was indeed real.
Counter-Strike: Global Offensive is Valves new take on the Counter-Strike franchise, although its not considered a full sequel to Counter-Strike. Instead, the game is considered a combination of Counter-Strike and Counter-Strike: Source that will be released on XBLA, PSN, PC and Mac. Dota 2 is Valves upcoming strategy game, which the company considers an "action real-time strategy." Newells 10" UI is a reference to Valves upcoming "Big Picture Mode," which will allow Steam and Steam games to be played on a television with an interface scaled to meet the increased size of television displays.
Newells comments would indicate that speculation the company would be teaming up with IGN to announce Half-Life 3 are likely false. This could mean the two may instead be teasing the "Meet the Pyro" short in Valves line of Team Fortress 2 short films.