I install 2 nodes with 1.8.3 zabbix-server-pgsql and frontend.
I followed http://www.zabbix.com/documentation/1.8/manual/distributed_monitoring to setup DM .
Master node correctly "see" slave node in the "node list" at top right of web interface.

I then enable the zabbix agent on the slave node. data are sent and a few seconds after, related events appear on the master node (when I select "slave"), but I can't see the agent in the configuration section, neither their graphs.
In the zabbix-agent log on slave node, I can see :

11102:20101022:151408.810 [Z3005] Query failed: [0] PGRES_FATAL_ERROR:ERREUR: la fonction md5(numeric) n'existe pas
LINE 1: ...||status||','||md5(macros)||','||md5(agent)||','||md5(time)|...
^
HINT: Aucune fonction ne correspond au nom donné et aux types d'arguments.
Vous devez ajouter des conversions explicites de type.
[insert into node_cksum (nodeid,tablename,recordid,cksumtype,cksum) select 2,'httptest',httptestid,1,md5(name)||','||applicationid||','||lastcheck||','||nextcheck||','||curstate||','||curstep||','||lastfailedstep||','||delay||','||status||','||md5(macros)||','||md5(agent)||','||md5(time)||','||md5(error)||','||authentication||','||md5(http_user)||','||md5(http_password) from httptest where 1=1 and httptestid between 200000000000000 and 299999999999999]

It seems the md5 is not made on a string but on an integer.