The good news is that Chris has decided to release a new version of the control that "will have full support of the ASP.NET AJAX Extensions." I built a proof of concept using the pushpin scenario from the control built by Chris. I reworked it using the ASP.NET AJAX Control Toolkit. If you have seen my Virtual Earth demos, then you've seen the proof of concept.
DISCLAIMER: This control was written as a "proof of concept" for my demos. It is "AS-IS" and not without bugs;). I didn't really think through all the hard scenarios that Chris will surely encounter. I'm really looking forward to seeing the final product from Chris.