One issue with this approach is that the author is allowing users to start the background work, rather than putting it into a queue like he had been doing with his prior site. If his site gets slammed, this will be a problem, whereas with a queue he could set up his interface to let the user continue browsing the site while his/her work makes its way through the queue.

One nice find from the article is the link to the Flash implementation of websockets: http://github.com/gimite/web-socket-js