I have noticed a bug/documentation error:
The above docs say the following about the session.save_path arguement:
"Each url may contain parameters which are applied to that server, they are the same as for the Memcache::addServer() method. "
addServer method's docs say:
"port
Point to the port where memcached is listening for connections. This parameter is optional and its default value is 11211. Set this parameter to 0 when using UNIX domain sockets. "
However when specifying the save_path, I have found that with PHP 5.2.3 and memcache 2.1.2 that the port is a *required* part of the string.
Hope that helps some people scratching their heads.