We used OpenXML in some components for a (small/mid sized?? - maybe 35K hits/day) web site generation app to pass small xml docs to some stored procs to vary the behaviour of what was being returned - one particular case replaced several recursive hits from the app to get out some hierarchical info in different ways (get children, get ancestors, get decendents, get grandchildren etc) - the queries were still quick and sped things up considerably in that scenario as well as providing us with some really flexible procs that we could reuse a lot ( less work! ).

I also tried using it for multiple insert/updates (throw an xml doc to the db, load into declared table and do joins/let it decide whether to do inserts or updates - I don't mean bulk bulk updates to the db here since I'm sure there's better ways to handle that, but editing multiple records in the app and passing it all along at once seemed quite nice since you didn't have to really worry about whether you were inserting or updating - just send the info.  This was only a small app though, so if anyone has done anything bigger like that I'd be interested to know how it went.

Ta

Jon