There have been a lot of high level discussions about sharing data among multiple systems (security, access rights, etc.) but this gets quite interesting when you actually have to design and implement it. This reminds me of the early days of email systems (circa 80's). The debate was between "standards" and loosely coupled systems. SMTP clobbered the big clumsy OSI standards.
And here we are again. It will be many years before the dust settles. The building blocks of this exchange are XML, RDF, JSON and metadata. (A very good primer here). XML is the lowest common demoninator in all these systems. The trick becomes mapping the descriptions between multiple systems. Which means we're going to see the rise of Meta Directories to accomplish this. Why? Although the behemouth IT firms will try to dictate with the Federal government these standards, the smaller providers and their IT suppliers will have not inclination to spend the time or money to make that work. For instance Epic's Vendor Relations group will not talk directly to vendors (sad, but true). Instead nimble IT firms will provide light weight solutions which get the job done without all the overhead. And those will evolve into what is actually used across the industry.
Does anyone remember IBM PROFS?