What are some good resources to look into synchronizing contact data on mobile devices with a .NET application?

Question

Basically we want to be able to somehow synchronize our .NET application's contacts with the contacts on a mobile device (Pocket PC, iPhone, Blackberry, etc) Preferably a one shot deal that can interface with them all but that doesn't seem likely.

Preferably also we're not writing applications (or at least very simple ones) for the mobile devices, but be able to sync with the built-in contacts feature of these devices, both sending from the device to our application and vice versa. For email we set up our application as an IMAP server and mobile devices can just sync that way and something like that would be ideal, but I suspect such a standard doesn't exist.

Are there any commercial libraries with a flexible API that allow us to do this?

In order of preference is PocketPC, iPhone, Blackberry, but info on any of these would be appreciated.

Answer 1

There are API's going to/from .Net and gmail, perhaps you could use a central Google account as the conduit:

Google Account Developers Guide: .NET - Contacts

Then there are ways then to go from gMail contacts to the smartphones such as Goosync.

EDIT: Another option could be to write a syncML driver for your application using SyncMLDotNet and sync to the devices via a free server such as Funambol.