I’m not sure how I didn’t see this earlier, but it looks like MySQL 5.1 is coming with a load balancer for replicated servers. I’m absolutely pumped about this - we’ve got a few sites running with multiple db slaves and it’s so annoying having to check if they’re behind the master.

It looks like the load balancer will automatically pull slaves out if they fall behind, and route connections to the ones that are the most up to date. It is based on MySQL Proxy, which is currently in Alpha.

MySQL Load Balancer