I just posted an update to my earlier work on creating an XML format for variable binding results from the RDF Data Access WG's SPARQL query language. This is not the final version, since I'm still considering two formats, one with XML schemas (RelaxNG and WXS) and one without. I've not been able to decide which one to go with although my preference is the non-schemas one as it reads cleaner to me. Writing XQueries for both forms didn't help me much, they both are relatively the same to query.