SHP2KML is a freeware converter for Windows that I came across the other day at FreeGeographyTools that could be helpful in getting your Esri Shape files on the web in Virtual Earth. V2 is out and appears to have a number of improvements over its predecessor, especially in the UI. Its 5 step wizard-ish interface made it painfree to convert to KML including some nice touches like choosing labels based on source data. Here's a few screen shots while converting a postcode boundary file to KML and importing it into a Live Search Maps Collection. [Click to see my Postcode Sample]

Step 1. Pick a file to import. The Preview window shows you the effect of your changes as you move through the wizard

Step 2. Pick a label field and type of symbology

Step 3. Based on input in step 2, set options for the style of resulting objects. Convenient options for overriding all entities and choosing pre-defined color gradients.

Step 4. Choose fields to be output in the description field.

Step 5. Output your new KML file

Pretty straight forward for quick conversions and plenty of options available for the tweaker. When the KML file is created, go to Live Search Maps, choose the Collections -> Open My Collections -> Import option to bring your KML into a Collection. from there you can do all of the usual stuff to the Collection including editing, tagging and sharing.