Tim,

this is good explanation of what I also thought about for large part of past 10 years or so -- while working on Midgard together with Bergie and now, that I'm trying to get some spirit into Sharing on Maemo being, among other things, an architect for that subsystem (mostly in Harmattan, as I came to Fremantle well after it has been shaped in this area).

In Maemo 5 our Contacts are flexible to include any additional field you see as needed. Other applications could then access those fields and relate them. Mauku, for example, provides a good abstraction over regularly updated streams of information where emphasis is placed on small informational chunks. It could have a backend that uses Contacts to combine data sources you have described. I hope we could enhance it as community. Bits are in place to enable such enhancements.