PostgreSQL has had memcached support for a VERY long time

No: this extension provides functions that allow SQL queries and store procedures to make outgoing requests to a memcache server; the functionality that was being experimented with in MySQL (HandlerSocket) and was recently implemented for the upcoming 5.6 turns MySQL into a memcached server, providing direct read/write access to an InnoDB table using the memcache protocol, bypassing the SQL parser and query optimizer.

(FWIW, AFAICT, the main reason MySQL needed this is because its prepared statements functionality is subpar. In specific, it does not seem to support preparing a parameterized statement and then saving the query plan to be used for a later bound set of arguments: when the arguments are later bound it is forced to re-optimize the query. I imagine that most of the same performance benefits of HandlerSocket could then easily be obtained using the PostgreSQL v3 protocol, albeit with obviously different client support.)

http://use-the-index-luke.com/blog/2011-07-16/planning-for-r...