'apachectl configtest' gives me "Syntax OK".
I just found that my apache error log complains about OCS_MODPERL_VERSION not being set:
[Tue Nov 10 00:45:31 2009] [error] OCS_MODPERL_VERSION not defined. Abort\nBEGIN failed--compilation aborted at /usr/lib/perl5/site_perl/5.8.8/Apache/Ocsinventory.pm line 28.\nCompilation failed in require at (eval 8) line 3.\n
Earlier on in the config is the line
PerlSetEnv OCS_MODPERL_VERSION 2
so it should really be set...
EDIT: Putting that line before the virtualhost definition allowed apache to start, but The Ocsinventory module is complaining about other variables not being set (which are set within virtualhost). I could put them all in the beginning, but the different virtualhosts need different configurations so I'm not sure it it would work well.