What are the security ramifications that one should be aware of when considering using WebDAV? How does one go about securing it? What else should I know about it?
WebDav by its self doesn't have any security. It'll let anyone touch anything. It says in the standards docs that this should be handled in the web-server layer (or application, if that's providing the WebDAV service).
It's basically the same as securing HTTP where resources can be modified: implement HTTPS and require authentication (password or client certificates).