I've just upgraded to Precise, and the problem is still there. The behavior seems slightly different now, in that when the windows are snapped to the side, the issue doesn't occur (or at least I haven't noticed it yet - it was consistent in Oneiric). When a normal un-maximized window is sitting on the bottom of a lower workspace and is called by clicking the launcher while in an upper one, however, it is still moved and sits between the workspaces. Now it seems not just to move down into the top a bit, but move almost entirely into the upper workspace, which is even worse.
I've just upgraded to Precise, and the problem is still there. The behavior seems slightly different now, in that when the windows are snapped to the side, the issue doesn't occur (or at least I haven't noticed it yet - it was consistent in Oneiric). When a normal un-maximized window is sitting on the bottom of a lower workspace and is called by clicking the launcher while in an upper one, however, it is still moved and sits between the workspaces. Now it seems not just to move down into the top a bit, but move almost entirely into the upper workspace, which is even worse.