Sound Shapes is the latest game from Jonathan Mak, the developer behind Everyday Shooter, and it has a similar, cool sensibility to it. It's striving to combine music and platforming in some pretty interesting ways, and it's probably the game that I'm currently looking forward to the most out of Sony's pre-E3 NGP lineup.
You control a ball, rolling around a 2D environment. You can extend treads to get a better grip on surfaces, letting you hang and roll on ceilings, walls, and most other surfaces, but you'll move faster if your treads are retracted. This leads to some cases where you need to get up some speed, jump, and then extend your treads in mid-air to stick to a wall. From there you might roll up onto solid ground and keep moving forward. The object is to collect items on your way, and each item makes up a different part of that level's soundtrack. So you're sort of filling in the music as you play. It seems like collecting different parts in different orders or at different times on your way to the goal will lead to a slightly different arrangement of the song. One of the ideas being tossed around is that completing a level perfectly would allow you to export your version of that level's music as an MP3. There will be around 30 levels in the game, though there are plans to add more after release.
The game also has a built-in level editor that lets you create one-screen levels that work on the same basic concept. Here, the music seems to be more important than the level, since you don't have a ton of room to work in. You'll drop drum, synth, and other sounds around the screen to plot out a loop. Then you'll need to put in some surfaces to jump on and cling to in order to make it possible to collect all of those sounds. Created levels can be uploaded, shared, and remixed by other players. The game will automatically maintain attribution for remixes, allowing for remixes of remixes of remixes while still crediting all the right creators along the way.
Visually, it's got a simple style that works for it, though it's also the sort of thing that probably doesn't exactly require the increased horsepower of the NGP to work. But that's the only place you'll be able to play it. This video from the PlayStation Blog has some more details directly from Mak himself.