I would just like to say something about vehicle creation within Blockland: I don't think it's how you would picture it to be, if it existed to make your vehicles without the use of other programs.
I think that if you were to be able to make vehicles without actually opening up programs like Milkshape that it would be in a GUI, much like the avatar creation menu. There'd be a set of wheels, wings, bodies, and other parts to choose from, as well as some basic forms for speed (with limits), acceleration, etc. The bodies would restrict how many wheels you could put on, as well as maybe the size of the wheel (classified inside a script about the pieces), where the wheels would be, and other things like this. As you build these things up you might see a 3D preview (much like the avatar creation menu) of what your creation would look like.
I think being able to have the community add onto this would be nice as well. The creator(s) would just have to provide a few basic pieces, then allow the users to have add-ons for the rest. All they'd have to provide is something like a wheel and a very basic script.
But as for building it in-game along side your giant houses and such? Probably not going to happen. I would like to see the vehicle-creation menu like I described though, and I do think that it would be possible to do. Maybe not easy, but possible.
Any input on this? Is it a bit more plausible than what most people hope for?
EDIT: Trader is pointing out some flaws like the datablock limit.