This morning we held a Move event at the store where I work - this time the Sony representative had 2 Move controllers, and that was a nice change as we were able to demo all the 2-Player action.
Start The Party CAN be played solo, but it's a LOT more enjoyable with two or more people. The demo we tried had a fairly decent set of minigames, quickfire challenges, etc. that are really very fun. They remind of of WarioWare in some ways, just with a far more precise control scheme.
Tumble is a bit like Jenga meets Boom Blox. It's a take on the stack-stuff-until-it-collapses thing, where you and your opponent get three blocks of various shapes and sizes that you must stack on top of one another, building for both a bit of stability but also to make it difficult for your opponent to build on your play.
Sports Champions was fun like before, but now I was able to experience the two player table tennis. It's just as accurate in lots of ways, but unfortunately the sun was directly behind us and was interfering with the camera and the Move controller's lighted orb so it sometimes wouldn't recognize motions properly. This really won't be an issue in pretty much any home out there, as most of you will likely have blinds in your room to shield your television sets from the sun's glare.
So... my biggest point to make. Be sure you have enough room between you and the camera/tv area. 5-6 feet at minimum, generally, is a safe bet. Most living rooms should have sufficient space.
Another thing Move begs for? Lightsabers.
Check out a video previewing the Move demo disc.