What do you get when people take online social networking to its logical extreme? Eastern Standard Tribe. In it, people organize by the circadian rhythm of their online groups, or tribes, like the group of the title, or Greenwich 0.
The book opens with the protagonist, Art Berry, being committed to a mental hospital as the result of an elaborate intrigue between time zone tribes - all over an idea he has about peer to peer file swapping between cars. From there we flash back to how he landed in this mess.
A quick tale about mental institutions and business partners who cheat, all set in a tomorrow where online communities cluster around time zone more than anything else.
Doctorow basically starts in the middle and then uses a "now" timeline and a "flashback" timeline to keep the tension high. It's a good trick, and works well. This was a fun book, and very fast to read.