Multiplayer PSP games with one UMD to be a feature, not a hack?

We reported earlier on a hack that enables you to play multiplayer games on the PSP with only one copy of the game. This stirred a deeply (well, not that deeply) buried memory in the hive mind that is Engadget, and we hunted down a Sony ad that's run on Japanese TV recently, which shows popular magician Tomohiro Maeda messing with a couple of PSPs and demonstrating playing a networked game on them with a UMD inserted into only one. The voiceover at the end confirms that there's a feature called Game Sharing that works at least in the game shown, Namco Museum, which is out already in Japan. Unfortunately the title seems to be a run-of-the-mill collection of Namco faves from the past; not like they'd encourage you to buy less copies of anything new, right? (The "Read" link below is to a Windows Media stream of the commercial.)

[UPDATE: OK, seems from the comments like this was old hat to some people. We promise to do penance by ritually beating ourselves with a whip made from UMDs.]