Chronobis is an Outlook Web Access (OWA) synchronization program. It connects directly to OWA from your PPC and doesn't require any special permissions from your IT department. If you can access OWA from a public web browser, you can sync with Chronobis. Chronobis also runs completely self-contained on your PPC, no need to install software on your desktop or use a "3rd party service".
Currently Chronobis is a one way (Server to PPC) calendar synchronization, but I'm planning on adding support for tasks and contacts as well as two way synchronization.
For more information, screen shots, and to try it out visit:
http://www.chronobis.com/