Check out what's being done in London to create a global sensor data repository - the YouTube of sensor data - that lays the foundation for interactive environments and remote sensing applications.
Dave - you seem to have a lot of knowledge of Pachube. I'm really interested in it, as it seems like it could provide a fantastic data foundation for DIYcity projects down the road.
I'm not sure I entirely understand where they are right now though with regard to their big vision, and how or whether we could build apps that take advantage of this foundation presently. And I'm pretty sure lots of other people on the site don't have the faintest idea about this either.
If you'd care to outline a simple idea for how a DIYcity-type application could build on Pachube, and what the outcome would be I think that would be pretty interesting to people, and it might give us some ideas for ways to use it.