Time to start hammering again - and working off my backlog of emails! I just made some small adjustments to Blunt to improve Windows support. Pairing is the first step, and it looks like initiating pairing from the Newton works at least to Mac OS X and my 3650.
I also investigated SyncML a bit. I’m not sure if Apple will ever open iSync enough to allow true SyncML integration… they seem to use server authentication from iSync, most likely to see .Mac services. Instead of using iSync and .Mac, my plan is to play around with my own SyncML server instead and see how much effort a SyncML client for the Newton might be. I got Sync4J running on my Cube, and the vCard and iCal files used by SyncML should be importable into Address Book, iCal and also IC/VC.