London Bloggers Tube Map

On the same downtown train as the NYC Bloggers Subway map, Cal has made the London Bloggers Tube Map. Again, the unfolding relationships between physical place/physical connection and virtual connections are fascinating ... It'd be interesting to see a layer of (Google-powered?) link relationships superimposed on top of the physical map i.e. I link to BBJ & Plasticbag, say (one of which is in an immediate 'geographical' network too). What does that mean? What logical (or illogical!) nodes emerge and how do they relate to physical nodes?