Open Thread: May 2010, Part 2

The Open Thread from the be­gin­ning of the month has more than 500 com­ments – new Open Thread com­ments may be made here.

This thread is for the dis­cus­sion of Less Wrong top­ics that have not ap­peared in re­cent posts. If a dis­cus­sion gets un­wieldy, cel­e­brate by turn­ing it into a top-level post.