"You can use memcached over a network (i.e., install
your web application on one server and memcached on another
server), but usually you install both on one server to avoid the
networking overhead. It should be noted the memcached is no
out-of-the-box solution for speeding up your web applications.
Typically you have to adjust your scripts (PHP, Perl, etc.) to work
with memcached, so this requires a little bit of
work."