The Biggest MySQL Cluster, Ever?

ExcerLee asks: "Our team is going to build a MySQL (load-balancing and fail-over) cluster for the Cluster World Expo in the end of June. This cluster is going to have at least 10 nodes, and will use dual-opteron systems from Polywell Computers and SuSE Enterprise Linux for AMD64 from SuSE. While we are working on this hefty cluster, we wonder if this is the biggest MySQL cluster has ever been built. I googled with terms like 'biggest mysql cluster', but didn't find much." If you've run a MySQL cluster before, how large was it and how well did it perform? Krow: I have been told of much larger clusters then this; Slashdot DBs total 6 machines with 18 processors, and LiveJournal has one of the most complicated clusters I have ever seen set up.