Many collections of lovingly arranged zeros and ones have recently wound their way through the tubes from our private development systems onto the public servers; some obvious, others maybe less so...
After you install GS3, be sure to check out the new Platformer starter kit. Brandon did a great job with this. In the past we haven't been entirely clear about whether starter kits are supposed to be complete games, or technology demos, or educational resources, so I think we ended up trying to do a bit of all three and not perfectly nailing any of them. This time around, the starter kit is exactly what it says on the tin: a good place to start when making more interesting games of your own. What's more, it has documentation! The "Getting Started with XNA Game Studio / Starter Kit: Platformer" section in the product docs walks you through the code, including tutorials on how to add powerups and parallax scrolling.