I saw one of these guys, Shep Doeleman, talk last year. What they do for this is nuts. They have to transport an atomic clock with them to each site, and something like a 20 of the biggest helium-filled disks available in a custom machine to each site (which is somewhere crazy, like the South Pole, the top of a mountain in Chile, a volcano, etc). And run them all at the exact same time.

They end up with something like 7 PB of data and process it all down to like a 10 MB image. They then throw the rest of the data away because they can't afford the disk space for storage.

I think they have serious plans for putting a constellation of satellites around a Lagrange point.