I am interested in learning whether there is a product/solution to meet
these requirements:

A small (<20) number of users with handhelds, potentially a mixture of
iPAQ/PocketPC and Palm devices that have their own local, editable
contacts app.
A central, net (with authentication) accessable, server which accepts
updates from & distributes updates to the handheld devices when they're
connected to the net (by modem, hot sync, network card etc.).
Ability for each user to have private as well as public categorised
contacts, where the private contacts are only distributed to that user,
but public contacts are distributed to everyone.

Those are the main requirements, but on the would-be-nice list is:

Central server Linux friendly so other Linux-based desktops could have
Other desktop Windows systems could also connect to the central server to
keep a local contacts DB up-to-date.
Cheap to free would be quite desirable too!

Does anyone know of anything that can do this?

Glenn Trigg
ggt at optusnet dot com dot au