Executives at AOL, MSN and Yahoo! were obviously reading my blog several months ago about the easiest way to put an end to spam. They announced today a plan to work together to create a whitelist of permission marketers (and, one assumes, that leads to a blacklist of everyone else).
Missing from this equation is the key part, imho—friction. I think we need to charge something (just a penny is enough) to make it expensive to send huge amounts of email where the expected return is quite low.