There are no less than four sessions about the concept of "Open Data" at this year's FOO (last year there was one).
Open Data is something I've been interested in for a couple of years now as a natural extension of Open Source (not unlike Open Standards). The idea is that your online data should be available for your use freely. There are still many large datastores that treat data you submit (or that is gathered about you) as a "proprietary resource". So for instance, how easy is it to manage your photos online? If you get tired of one photo aggregation system, how easy is it to transfer your assets to another system? Do you "own" those photos? You certainly own the copyright, but do you own them from a practical point of view if you can't manage them?