The official Lego Universe site has some images of the game "in action". They all look at little concept-y to me, but if it's a rough approximation of what we can expect from the game then I'm interested. Gleaning what little we can from this shots, we can see that it's going to have a Lego minifig spin on the traditional avatar creation and customisation, while the game is probably going to feature collaborative building projects of some kind - we can see a monument and a rocket here.
It's also going to feature pirates and ninjas. Which makes sense. Could this be the next big thing for Lego videogames? It's certainly intriguing, and the idea of being able to construct things from virtual Lego and then port them into the game world makes this an interesting overlap with the Second Life world-building themes that usually get left out of game-like MMOs.