Hi5 at SF Java Meetup group
If you missed Monday’s talk by hi5’s Paul Lindner, you missed a great presentation. Fortunately, the slides are available on the meetup group’s page. Paul talked about the true ins and outs of running a hugely scalable, high performing social networking site. A lot of the architectural points he made are applicable to more than just social networking though. Basically, they do a ton of caching, a ton of monitoring/profiling, and just generally really clever use of resources, both hardware and software. Oh, and they also use Resin. 
Paul claimed hi5 to be one of the largest users of Resin.