Judging by the perks (Info which leaked the other day), it does indeed look like you'll be able to build a settlement at each build-site (Or workshop settlements as they're referred to in the thing I read), and link them together with trade and such. I just can't wait.
Considering that modders made stuff like this for New Vegas which didn't have anything like it to begin with, I think we can safely expect the number of build sites to increase DRAMATICALLY once the CK comes out
Probably have to wait till they release the updated Geck. Which I think was like 6 weeks after each release of FO. If I remember right.