It's a programme where you can make your own lego designs on your PC.
Which is about time b/c LEGO's been making a whole bunch of computer games where you couldn't do that.
But after you've made your own design, you can upload it to the community website for others to peruse, and if you want, you can buy the pieces for your custom design and have them delivered to you so you can make it in real life.
As a kid, I knew that this program would exist eventually..
Now that I actually have it though, all it does is make me want to dig out my old boxes of bricks. It's really hard to build 3D things on a 2D screen and have it all come out right. And this seems much more geared toward knowing what you want to build, rather than grabbing a handful of random bricks and seeing what comes to mind.
I'll have to give this a spin, I've been contemplating the newest iteration to the Lego mindstorm line which seems to be a great improvement over the already good first gen.
I worked on one of their videogames a few years back, they used to have a rule that we couldn't put anything into the game that you couldn't build with bricks you could pick up off the shelf.
This led to the comedy gold of a room full of trained CG artists with buckets of lego building models of houses and cars before painstakingly building them again in 3DS Max.
Even now they claim that the mere sound of lego bricks swishing in a bucket brings them out in a cold sweat.