There are quite a few ways of connecting hubs and rods. The previous thing used a central hub contained the 'socket' and the rod contained the 'insertion'.

This thing reverses the order. The 'hub' contains the insertion, and the rod contains the socket.

Why reverse the order? I thought I could get away with less plastic on the hub. turns out it's probably the same or more than the original. I also wanted to make it much easier to strengthen the overall connection, particularly at the rod. I think this design is much stronger for the rod part of it.

Like the previous design, this allows you to construct a vertex with multiple rods, and they can be at a broad range of angles relative to 'flat'.

The joint is made in such a way that you can slide the rod connector along, but when there's any pressure on it, it will hold firm. that's nice because you can move them to where they need to be, micro adjust, and just leave it after that.

Really it's just an experiment. I was also going for reduction in support material. It still requires some, but if that can be reduced, it will be very good.

UPDATE: 06072011
Added the obligatory tetrahedron construction using the parts.

1) Print a whole bunch of hubs, enough of the type you need to construct whatever space frame you're building.
2) Print a whole bunch of the rod connectors. Enough to go on both ends of whatever rods you're using.
3) Put the 'grabbers' on the rods
4) Slide the grabbers onto the hub spokes, and position them appropriately
5) Rejoice!

I'm sure it can be done with less plastic. I'm sure this is a moldable design as well.