My understanding is that on the kitchensync side, that support is present or forthcoming for the DTM-based apps (i.e. the ones that come with the stock Sharp ROM's). Again, I haven't upgraded to KDE 3.3 yet b/c it hasn't moved into sarge (if you can get it, I'd love to know if it works or not). I don't know if/how kitchensync devel's would add support for KDEPIM/PI, although one would think it would be a LOT easier than getting the DTM format to work.
Otherwise, you can sync ical/vcard files directly from KO/Pi and KA/Pi. There are a number of resources telling you how to do this, please RTM. Also, I believe there's an app for KDE called ksync, which allows you to sync ical/vcard files (regardless of what app they belong to). If you can set up a TCP/IP connection btw. the Z and the desktop (ssh is a good choice), you should be able to set up a sync'ing "pair" between the ical files on the Z and PC, respectively (ditto .vcf files for KA/Pi and kaddressbook).
I may have time to tinker with this this weekend to see if it works. . .