LSC,
I would have been far more impressed if he said that he was serving 1500 users who were UPDATING the database. I think there are a lot of solutions for a web server that can support queries. There are fewer solutions when reliable updating is required. Even for queries, your mileage can vary, are they all requesting data that is similar enough that the database is able to cache the needed blocks in memory? Just for curiosity I looked at www.tpc.org, and I don't see MySql listed anywhere.