Version 0.6 has been released, the big news is:
What is discovery mode? It means that a table found by one MySQL server can be found by another who has access to the memcache cluster. This works because on CREATE TABLE a copy of the definition of the table is placed inside of the memcache cluster for other MySQL servers to find. This is not perfect yet and it will need a bit more code to really scale (aka it needs resource counting). This version has gotten quite a bit more outside testing then previous versions so I expect quite a few SQL errors are now gone.
You can find the announcement here:
http://tangent.org/index.pl?node_id=506
The download is here:
http://download.tangent.org/memcache_engine-0.6.tar.gz