Add to the front page.
I had to read a forum post to learn that Zimbra was built for Linux, and might get built for Mac OSX. People shouldn't have to dig so far to learn what platform software was made for. Put the info on the homepage where people can easily see it.
Also, what server and database software does it work with? Apache? PHP? MySGL? Any talks with site control panel people (such as cPanel) about including Zimbra in their packages?
We plan to support many OS's in the future. So the fact that our beta release is only available on Linux is something we don't feel is right to list on the home page. In fact serveral developers on the forums here have reported success porting Zimbra to other OS's already. If you've got an OS you'd like to see Zimbra on please vote here:
If your up for a challenge try to port it yourself. Others have and seem to be to having great success.
Zimbra includes all you need to run. For the record we use Tomcat and MySQL. If you'd like more details you may want to start here:
If you just want a list of all the other open source packages take a look at this list: