Two companies are in the process of launching MySQL appliances: Schooner Infotech and Virident. Both incorporate flash in some form and it will be interesting to find out what value they add. I also want to know how they overcome some of the performance limits in InnoDB for multi-core and high-IOPs servers. The problems on multi-core servers are well known. The problems on high-IOPs servers are slowly becoming understood and there are fixes in the v3 Google patch and in Percona binaries.
Do the appliances use official versions of MySQL? The schooner web site states that InnoDB 1.0.3 is used, which goes a long way towards improving performance on servers with 8+ cores.
I will describe some of the IO problems and improvements during my talks at the Percona Performance Conference and the MySQL Conference.