Allow me a moment to gloat if you will.
From January of this year:
That would mean announcement at GenCon 07 with the game coming a year later. I keep hearing people say they think WOTC is just going to "spring" 4e on folks, show up at GenCon one year and say "here it is!" but I think we'll get PLENTY of notice. This is a launch on the scale of the PS2 for the company. They will not spring it on folks.