I'd like to use that howto: http://howtoforge.com/server_monitoring_with_munin_monit_debian_etch with ispcfg3 with a vhost running suPhp is that possible?
Yes, it is. You only have to modify "htmldir" in Munin's configuration file to point to the appropriate directory and Apache part of Monit's configuration. Munin and Monit don't need php to work.
the problem I had was with the part, where you chown the output folder munin:munin but I solved it by moving the output folder into the default vhost which doesn't run suphp.
we seem not to understand each other: if I put it into a directory, within a vhost running suPhp and then chown it by munin, munin will write to it but apache will not be allowed to display it as suPhp wants a different owner:group than munin:munin OR, and this just occured to me, being all html files, maybe it will work? anyway, works now as I moved it into a non-suPhp vhost