Trailer:
http://www.gametrailers.com/video/ces-10-lego-universe/60584

Gameplay:
Part 1 - http://www.gametrailers.com/video/ces-10-lego-universe/60652
Part 2 - http://www.gametrailers.com/video/ces-10-lego-universe/60650
Part 3 - http://www.gametrailers.com/video/ces-10-lego-universe/60648
Part 4 - http://www.gametrailers.com/video/ces-10-lego-universe/60646

Screenshots/info:
http://www.mpogd.com/news/?ID=5221

The game is an online platformer, which mean there's no levelling. You attack in real time, rather than click to auto-attack as you do in WoW for example. You customise your character's abilities or role in combat by changing the equipment you're wearing. You can unlock stuff to customise your appearance by completing quests or achievements.

There are three ways to build things:
Quick (auto) build. An example of this can be seen in part 1 where he rebuilds a destroyed enemy robot into a friendly sentry gun. Quick building uses up 'imagination', which is similar to mana from what I understand.
Schematics. You can see this in part 2 I think, where he builds a rocket ship. You don't have to follow the schematics exactly.
Free build. Build whatever you want from parts you've unlocked through quests, achievements, finding treasure/secrets etc.. Once you've built whatever you want, you can bring it to life by giving it a "behavior." From what I understand, you are able to modify the preset behaviors.

Obviously the game is going to be aimed at a young audience, so the game will be moderated. You can see in part 1 that your name is sent to a moderator upon character creation, and is soon after verified. Until it is verified, you can still play the game with a default name. This will put a stop to stupid names without getting in the way of playing the game. The things you build are also moderated. This is a good thing, seeing as it'll stop a whole lot of buildings that resemble dicks, or buildings that have dicks.

I've pretty much liked every LEGO platformer game so far, and this one looks like it'll be similar but with MMO elements. Looks like fun.

Looks like a lot of fun.

I want it.

All of the "imagination design" elements, or building or whatever you want to call them, look really cool, and the game looks really fun. It's like a lego game + a bit of LBP (unlockable items for lots of customizable character options) + a tiny bit of WoW (the loot box at least looks similar). It does still seem to retain the platformer feel, which should make it a very interesting, unique MMO. Everything seems to be very streamlined and solid. This looks very promising!

I didn't really see anything about a planned release date, but I did notice they said they were in alpha testing?

I think the release date is some time in the third quarter of 2010.