||Resin: The Instant Application Server|
Resin has been flying more or less beneath the radar for quite some time now, and although it's not GPL open source, it is 'developer source.'
I've used it load balanced in high-volume environments and have been amazed even by httpd
performance. Yes, you can load balance the VMs.
Yes, it has the best MySQL/JDBC driver available
built-in. Built in connection pooling. Strong community discussion and support, and their developers are great (they listen, and have
daily builds). Can't speak highly enough of it.