Aquatix was asking on a post or two ago about, “How is deprecating webdav a good thing?”
The problem with webdav is that while webdav is meant to be a standard, I’ve rarely met a client that handled it properly. I would also point out that some of these problems were not implementations with the client, but implementations with the server side and the relation to the client.
The new model in Exchange 2007 is to deprecate webdav support in favor of web services (via SOAL/XML, etc.). This is a boon for clients because it uses a standardized model to feed data and the response is just XML. How badly can a client screw that up? That means the server-side is no longer an equation in poor Exchange support.