Gravity wave detectors are in development now; they are expected to be able to observe very distant and very ancient gravity events.
http://archive.ncsa.uiuc.edu/Cyberia/NumRel/LIGO.html
The problem with using gravity waves for communication is the difficulty in generating detectable waves; perhaps a pair of neutron stars could be electrically charged, then they could have vibrations induced by variations in the surrounding electical fields; these vibrations could carry data (I think) if done correctly.
Interestingly, some brane theories suggest that gravity waves could carry information into adjoining dimensional planes, whatever form these might take; to oversimplify appalingly, we could use gravity waves to communicate with other universes...