ThisIsMyNext's sources say that the next version of Android will most likely be called Jelly Bean. However, we don't know what version number it will be. Normally, I'd say ICS will be Android 4.0, especially since they're thinking about unifying the phone and tablet versions. It wouldn't make much sense to call it 3.xx, since that is the tablet version, and it would make even less sense to call it something like Android 2.4, because that will seem backwards when you have the tablet versions at 3.xx.
Google launched Android 1.0 in the fall of 2008, then Android 2.1 came in the fall of 2009. Gingebread should've been Android 3.0 in the fall of 2010, but they left that for February 2011 with Honeycomb. So I would expect Android 4.0 to arrive this fall, but ThisIsMyNext also says there will be some "game-changing stuff" lacking from ICS, that got pushed to Jelly Bean. So what if that means Jelly Bean will be Android 4.0 and being launched again in January or February, and once again "in time to fight off iPad 3"?
Hopefully, those features that got delayed weren't a big part of Ice-Cream Sandwich, and it will still be awesome. And the tipster says it will be. Together with the unification of phone and tablet versions, we should also see some major changes. ICS will have some "major architectural, functional and design changes" according to him, so it looks like it won't be just a slightly improved version of Honeycomb.
Ice-Cream Sandwich is expected to arrive first on the Nexus Prime this fall, possibly October 10th when Google is holding an event of theirs.