I tested the ZCO 5.0.18 in my case with outlook 2010 and it didn't work very well. This test machine didn't have ZCO prior to installing office 2010 and after installing office 2010 I tried to install the connector and it completed but failed installing the profile. I tried to add a zimbra email account through outlook 2010 and it failed saying "this information service is not installed on your computer". I also tried to go to control panel/mail and add it and got the same error message.
I'm not sure if anyone else has been testing this connector with outlook 2010. Obviously this only a beta but I think its pretty important to us to have the connector working for when outlook 2010 gets released.
Has anyone else seen this or tested outlook 2010 yet?