Many people (including me), get:
Couldn't find any pid file in '/data/deploy/cortland/releases/20080623202133/tmp/pids' matching 'dispatch.[0-9]*.pid'
This is because you’ve (correctly) started your mongrel with mongrel_cluster, and it does not create the PIDs with the same name.
To fix this, change your mongrel_cluster.yaml file to say:
pid_file: tmp/pids/dispatch.pid