With his own code he connects existing systems in unexpected ways (e.g. Library Lookup). He creates simple tools that encourage us to create and share our metadata (e.g. transparent feedreading, recent experiments in screencasting and InfoWorld's metadata explorer). For that matter, he regularly shines his journalistic light on projects that illustrate the emergent magic of collaboration and metadata (for example, wikipedia, bloglines, del.icio.us , flickr, and of all things the inspired heavy metal umlaut screencast).
Jon doesn't need my applause, but there's a reason I'm pointing to so much of his stuff here. I've been a fan for a long time and David's observation gave me a name to put to my favorites of Jon's work: it's all about playing well with others.