The Virtual Earth v3 control supports using GeoRSS as a datasource. To see how, select "Work with layers->Add GeoRSS layer" from the treeview at http://dev.live.com/virtualearth/sdk/. One of my coworkers made me aware of a nice little tool which will batch geocode delimited data for you (http://www.batchgeocode.com/). The output is still just delimited data, but you can use it to build GeoRSS xml using your tool of choice (xml capabilities in Excel for example). Of course you can jam it into a database as well.
Technorati Tags: Microsoft, AJAX, Windows Live, Web 2.0