"So how do you do what they did with MySQL. Can you build an always available multi-master cluster that is available, partition tolerant and eventually consistent?"

Obviously in the article they picked Riak. So yes Riak and other Dynamo-type database have those properties. I asked if the properties of Riak+custom eventual consistency code can be achieved with MySQL (as one of the above comments was asking people to maybe not jump to all these fancy and exotic solution when MySQL is available)