As far as has been announced, the Uncharted 2 Beta is US excusive, although Even Wells of Naughty Dog has said that they are working on getting it set up in Europe as well. [PlayStation Blog]
It won't be included with inFAMOUS. Some other means of participant selection will have to take place.
Judging from the incredible sales of the Wii, I'd say that motion controls are a big deal. While they may very well end up a gimmick for most people who have played games since before the Wii, motion controls have brought in an entirely new group of people, people who may never call themselves gamers, but effect the industry nonetheless.
On one extreme, that could mean that one day, all "hardcore" games are replaced by motion controlled, casual games. On the other end, successful Wii game sales could help developers fund more ambitious hardcore games on systems that cost more to develop for.
So far, there hasn't been a lot of compelling software announced for it. Tiger Wood 10 (EA Sports), Grand Slam Tennis (EA Sports) and Wii Sports Resort (Nintendo) are the only three games I can think of that actually use the add-on at this point. If sports games aren't your thing, I can't see why you'd be excited for MotionPlus.
I am still waiting for a MotionPlus game that piques my interest.
It depends on the stability of the surface the console will be placed on as well as the amount of "breathing" space there is around the console.
If overheating is an issue, the standing position actually allows for better heat dissipation, as heat rises and both the PS3 and 360 have vents on their tops in the standing position. This position also exposes more vents to open air, depending on your entertainment center setup.
However, if stability is the primary concern, laying the console down is probably safer. The 360 in particular, has a history of scratching discs when its orientation is shifted during play.
I would guess that all of the answers supporting the horizontal position are from people who have experience with the PlayStation 2, which also had disc scratching issues. With games being more expensive now, better safe than sorry, I suppose.
Note: Both of my consoles stand upright.
The sizes vary depending on the lengths of the videos, but the 30 minute shows are about 400 - 500 MB, with 2 hour movies coming in at close to 2GB (1.6 - 1.8GB). There are also shorter offerings, such as the animated Watchmen graphic novel chapters which are around 200 - 300MB for 12 - 20 minutes of video.