Yeah - a common setup would be something like an Exchange Server to which the Outlook clients on each person's desktop connects and which can host collaborative information such as shared calendars etc. Give each individual a PDA and they can sync up each time they are at their desk. Outlook may also support some collaborative features without an Exchange Server but I can't remember. However maybe you're thinking more of a web based system that centralises such information or something like that? I'm sure they exist but don't know of any specific suggestions offhand. Do a search for terms like "online", "collaborative", "workgroup", "calendar", "PIM" (Personal Information Manager) etc. to see what comes up.
In general Palm based PDA devices are cheaper than Windows Mobile/Pocket PC versions. You would really want to figure out your requirements in this area a bit more clearly rather than rushing to a decision and hacking some half baked solution together which might or might not work though.