Currently as far as I know, there is no way to have group calendars, addressbooks, files, and such mounted automatically. It has to be done manually on each user or scripted via command line.
In my opinion this would be a nice on/off option. Marketing group has marketing calendar, briefcase, and address book automatically added, but they also have the option to manually add Customer Service and Billing Calendars or somethign along those lines. But that's all in my dreams atm.
Mail | Dell 2950III | 2x Quad Core 5420 | 8gb RAM | 6x 146gb SAS RAID 0+1 | Red Hat 5.3 | Zimbra 6.0.10 Network Edition
Test | VMware ESXi Whitebox | Phenom II Black 3.2ghz | 12gb RAM | 6x 1tb SATA RAID 0+1 | CentOS 5.4 | FOSS, Not in use now