1.0-beta2 is released for general testing! Contains important bug fixes!
With the recent developments and with an updated, asynchronous benchmark client, performance of mdcached is marked at upwards of 210,000 transactions/s (a single, multi-threaded daemon on a 2x4-core 1.86 GHz Xeon), using unix local domain sockets. Real-life performance is expected to be around twice as much since the benchmark program is stealing CPU ticks from the daemon.
I've got a new idea for mdcached so I'm resuming development on it (actually I'll restart it from scratch).