I agree with your idea.  I have recommend that the ARRA use an underlying terminology (including what is called a controlled vocabulary) to provide the common vocabulary for all ARRA participants to use in organing what they mean, how they say it (data), and how they display and manipulate it (technology).

I agree, but with the caveat that the taxonomy needs to balance "comprehensiveness" with "manageability." It's really easy to say "simple," but it can be darn hard to actually pull that off. I'm sure whatever group gets tasked with nailing down the taxonomy is going to be pressured to incorporate everything under the sun. Not only will this make the taxonomy NOT simple, but it will lead to an undue burden on the various data creators.