I have setup with two nodes located on the same host, so the connection 
strings look like

1:  'host=dbserver dbname=production_main port=5432'
2:  'host=dbserver dbname=production port=5432'

Slon process for node 1 start with no problems. However, slon process 
for node 2 will not start if node 1 is already running. I traced the
problem to get_pid()  in /slony1-engine/tools/altperl/slon-tools.pm. It 
appears that the regular expresion in the following line matches 
connections string for both node 1 and node 2 when invoked for node 2.

*my* $command =  ps_args() . *"| egrep \"[s]lon .*$CLUSTER_NAME\" | egrep \"host=$dbhost dbname=$dbname.*port=$dbport\" | sort -n | awk '{print \$2}'"*;

I guess it could be fixed by changing egrep regexp to something like

**\"host=$dbhost dbname=$dbname[ \t].*port=$dbport\"**