Tutorial: Data Discovery Portal from the US Virtual Astronomical Observatory. Also available as a screencast: http://bit.ly/xwyyyb.
The Data Discovery Tool is only one among many that is accessible through the US Virtual Astronomical Observatory. More tools have been developed by observatories around the world.
The problem they faced years ago was that astronomical data was too voluminous to be easily transferred to users in bulk for local analysis. So, the entire community set about creating protocols for interfaces with that data, wherever it was stored. Which enables the analysis of that data remotely or downloading very small subsets of relevant data.
This does not diminish the importance of semantic mappings as nomenclature changes and as new theories spawn new terminologies. It does give a framework within which mappings would be useful.
I am sure there are other scientific data sharing initiatives that I have simply not encountered. Your pointers and suggestions about the same will be greatly appreciated!