Any chance on ignite realtime picking up the roundcube project. This would be really exciting.
Roundcube is an ajax webmail client. It is only in early development, but it is already very usable.
I believe that if RoundCube was in the hands of the OpenFire Developers you could create an email application that rivals that of gmail.
On the enterprise site, also incorportate your forums suite.
Have a look.