I doubt there will be a flood of comments on this, so I won't make a new thread, but it's interesting enough to append here.

Longer-Baseline Telescopes Using Quantum Repeaters

Today's best optical and infrared interferometers use baselines of only a few hundred meters at most. The limitation is due to photon loss and uncontrolled phase shifts (due to vibrations, for example).

This proposes the future use of quantum entanglement to allow arbitrarily long baselines for optical and infrared interferometric arrays.

http://arxiv.org/PS_cache/arxiv/pdf/1107/1107.2939v1.pdf

"For radio frequencies, interferometry can be performed robustly today even between telescopes spread across the planet. Optical frequencies are much higher, so fewer photons arrive per second, making interferometry much more difficult. In telescope design, the arriving light is usually treated classically, but when the number of photons arriving is small, the quantum state of the light may become important. Thus, the fi eld of quantum information is well-suited to provide advances."

"Time is what prevents everything from happening at once" - John Wheeler