NASA has shared data and software for years but now has a shiny new website and to be fair, some introductions to make sure of the material easier.
I don’t have a citation for it but Jim Grey (MS) was reported to say that astronomy data was great because there was so much of it and it was free.
There is a lot of mapping possible twixt and tween astronomy data sets, both historic and recent, so it is a ripe area for exploration with topic maps.
Update:
NASA’s Open Government Site Built On Open Source, an InformationWeek post on the NASA site.
Why InformationWeek mentions Object Oriented Data Technology (OODT) and Disqus but provides no links to the same, I cannot say.
Admittedly I don’t do enough linking for concepts, etc., but I do try to put in links to projects and the like.