Does closing the lid not still causing it to go to sleep on its own? I have my old MBP setup to go into deep sleep by default when I close the lid, but I don't need to watch it. Just close the lid and throw it in my backpack. Not being a troll, I am actually curious if the behavior has changed because I am looking at buying a new one.

This would undoubtedly be a useful little tool, but I feel compelled to point out that there's another free app called SmartSleep that can be set to automatically revert to the slower sleeping method (writes contents of memory to disk) when the battery is below 20%, which is, IMO, a little safer than risking losing anything you may have forgotten to save.