9to5mac‘s Mark Gurman is stating that they’ve heard from reliable sources that Lion will be out on the 14th of July (which ironically jives with a fake document that was sent around late last month, but has nothing to do with it). This date apparently corresponds with rumored release dates for new Macbook Airs, which are due out in mid-July. It was widely reported that Apple is holding back on updating any more of their hardware before Lion is out.
The server version of Lion will be out on the Mac App Store that day as well, though it will cost $49.99 instead of $29.99 for the regular version of Lion.
As with all updates that don’t rely on physical media, this date isn’t set in stone: if any last minute bugs are found in this GM, then Apple will be forced to release another seed to developers, and make certain that the final shipping product is as flawless as possible.