I just added some new addresses to my address book and found a cool mapping feature that I believe is new in 10.2. After I finished editing the cards, I double-checked the addresses and clicked the address type (e.g. home or work) and up popped a context menu with a single item, "Map Of". Click on this item and your browser will open to mapquest.com.
[Editor's note: There are actions associated with most of the other Address Book fields as well; click on the category label for each to see the choices.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020916054242818