I made the upgrade to 11.10 and have no linux pros around to help me. Window snap was working fine in 11.04, and now it doesn't. I've been to ccsm, it's checked, so I tried unchecking it, logging out and back in, checking it, and logging out and back in again.

I don't have an installation of 11.10 available right now, but I seem to recall there is a Unity section in ccsm (down near the bottom, I think) where you can gain better integration of the compiz effects with Unity. I had to use that with 11.04 to get some of the more elaborate effects.

A correction: my memory must record things upside down - the correct place is at the very top of the ccsm page. To activate all the bells and whistles, go to the Desktop section and uncheck the Ubuntu Unity Plugin; also uncheck Desktop Wall and check Composite, Gnome Compatibility, and OpenGL. That should do it (at least it did for me).

That didn't help, I have tried resetting the compiz settings to default, and Unity Plugin's already unchecked, Composite, Gnome Compatibility and OpenGL are already checked.

Solved: compiz --replace did it for me.

The previous post was to soon; compiz --replace did fix window snap, but it broke more than it fixed.

Instead, I found that logging in to Unity rather than Unity 2D (the option is in the menu found by clicking the gear in the log-in screen next to the name of the user logging in) fixed it.

I don't have any idea what's going on behind the scenes, I read a short summary that said that the difference between Unity and Unity 2D is that 2D doesn't have its own window manager, which kind of makes sense. I hope this helps anyone else, I know I was frustrated for quite a while.