I installed CompizConfig-Settings-Manager and I put on all the settings I liked and had in 11.10, including the ability to drag my windows to the adjacent workspace. It's under the Desktop Wall section, on the Edge Flipping tab and I've checked "Edge Flip Move" and "Edge Flip DnD."
In 11.10, the movement was smooth between each workspace, and the window would still be "grabbed" in the same place. In 12.04, it's leaving the window behind and the mouse appears to be "grabbing" nothing, but I'm still holding onto the window, and I can still move and place it within the workspace (or indeed the previous workspace as it won't appear in the desired place until I drag the mouse all the way to the edge of the screen).
Any way to fix this? I'm running 12.04 beta 2.