If you're using the web-client of Hotmail or Office Live you may already have discovered that "Hotmail now integrates with Bing Maps". When you create email, you can insert various types of content from Bing, including Bing Maps. Selecting "Maps and Places" a task pane opens that allows you to add new locations or interact with a set of previously defined locations. By default you'll find here the address that you entered in Windows Live profile. If you add a new place you've the option to store it for later use in Bing Maps Collection and quick pick it from the list. Once you made a quick pick from the list or geocoded a new address you can optionally edit the details and then insert it into your email.
See the screenshot below, in order of the post: