Hi all,
First of all, thanks again for all your feedback, it's really appreciated.
I would like to announce that we have already chosen the official replacement for eGroupware in Zentyal. It will be Zarafa and the first beta is going to be included in the new Zentyal 2.0-rc2 installer.
We know that many of you proposed Zimbra, but as we have already mentioned, Zimbra is more a separate appliance than a component that can be integrated with Zentyal. Contrary to that, Zarafa is fully integrable, as its dependencies are the same as the Zentyal ones (Postfix, Apache, ...) and it doesn't includes its own software, which also makes the maintenance more difficult.
Additionally, we feel more comfortable with Zarafa as we have been working with a customer on Zarafa integration and they are very happy with an experimental Zarafa integrated with Zentyal. So far, the feedback has been very positive. For example, the synchronization with mobile devices works out of the box.
Finally, Zarafa provides the most popular features that were used in eGroupware: contacts, calendars, tasks... so we think is perfect as a Groupware module.
Anyhow, we want you to know that we have not forgotten the Zimbra integration that has been proposed by many of you a number of times. One community member has already sent a Zimbra integration HOWTO and we hope to give it a good look soon as well as to be able to include it in the official documentation too.