Update: We fucked up again. Very sorry. It's only out in the US. We hate ourselves more than you can appreciate.
You may have believed us when we said the Mercenaries 2: World in Flames demo was up on Live. We lied. It is, however, there now. It's the game as you'd play if you bought the disc, but there's a 20-minute timer on it.
Try it. If you like it, buy it.