Gaia will produce quite a lot of data, approximately 200 TB over 5 years, according to this Wikipedia article (http://en.wikipedia.org/wiki/Gaia_(spacecraft)), however that feels a bit hand-wavy. Even if we assume an order of magnitude error, and its more like 2 PB, it is still far far less than the 15 PB (images plus metadata) that will be produced over 10 years with the Large Synoptic Survey Telescope. And yes, the LSST is driving a large number of distributed computing research projects because of its unique processing requirements.