Is this possible? I would love to be able to access my computer easily from a PC over the 'net!

Easily done, just Go > Connect to Server... in Finder, and type in the web address of the WebDAV server/directory. Like http://localhost/dav/, or any remote host.

It is much goodness. The drive can remain mounted even when you disconnect from the network, since it only sends data over the connection when you try to use it. Useful for a PBG4 owner like myself. :)

iCal is subscribing OK, so it must be partially set up, but now I cannot access it via the Finder.

Entering http://iborg.local/dav/ results in the Finder error: "-36" and the Console says: "/sbin/mount_webdav: checking server URL: Operation not supported by device".

Any ideas?