David,
I'll invite others to chime in here, but will give you my take on syncing in general.
We've been busy working on a couple of both offline and online untethered approaches to Centric CRM.
First we worked on a true offline version requiring no app server, and no database. We got pretty far on the technology, but have not done any significant development there for a while. We got to the display and datacom parts ok, but haven't actually gotten to syncing yet.
Second, we've been working hard on webdav support for tasks, calendar items, contacts, and files. We've got a lot of the work done there, and you can see some of it on our 3.0 release. More is coming soon. This is an online/offline model, but wouldn't be of help to your boss and his Symbian phone.
Third, we've got a partner who has done a Blackberry interface, but it is an online model, which in many ways I like better.
Syncing is hard, though there are now some tools available to make the task easier. Most everyone uses a proprietary product to do syncing, and we don't like to use proprietary products. I suppose we would if we had to.
So what does all this mean? We've got a bunch of offline initiatives going, but I'm not sure any of them would be of use to your boss. We would welcome you to join our community and develop something if you are up to it. We don't have any Symbian knowledge, but we'd provide all the support we could to make your job easier. We'd want to ensure that your contribution could be merged into the core code so we could carry your stuff through our upgrade process. We'd happily start a project in the community site for it and invite others with like interests to join. We would manage the team if you want.
Want to talk offline about the possibilities? I could email you directly if you want, or we could talk right here if you prefer.
Tom