An intersting Article about semantic layers and Colombia
Here's the link BBC NEWS | Technology | Smart tech reconnects Colombians
If you don't want to read it, what they're saying is that around 10% of the population of Colombia are displaced due to conflict, and whilst most are registered on a database, there are several databases operated by the government and NGOs such as the Red Cross. Problem is that the databases are incompatible.
The article talks about a new group using semantic web technology to pull the most important info from each database into a new "semantic knowledge layer" so that families can search across all databases simultaneously. My guess is that when a match is found they'll be directed to the relevant database owner for more info about their loved ones.
Thought the DB people might find it interesting.