Tipster ConsFEARacy stumbled upon this NeoGAF thread which leads to the Web site of the guy who created Echochrome. You'd think this site would only contain media about the game and a bunch of useless facts, but no, there is actually a playable demo ready for download.
But before you download anything, you have to remember that this demo was created before Echochrome was (presumably) submitted to and picked up by Sony, so you can't expect an overwhelming amount of polish or a finished game. But what you can expect is a fun little level editor that can easily entertain you for a while.
If you thought some of the levels shown in the E3 trailer were cool, just wait until you see what's possible in this demo. It'll also give you a feel for what Echochrome will be like so you won't have to blindly buy the game when it becomes available on the PlayStation Network and PSP.
Now go download the demo and post your craziest levels in the comments.