Microsoft has launched a public beta of the MSN Expo Live service as well a FAQ.

MSN is pitching Expo as an “online marketplace and social networking site.” Users will be able to target postings not just regionally but also nationally and to trusted groups like Messenger Buddies and coworkers.

It’s smart of Microsoft to leverage pre-existing groups like Messenger Buddies rather than forcing the user to recreate their social network through invitations.

One of the inspirations for Expo is clearly the Micronews– like many companies Microsoft published an internal newsletter with classifieds. When I was working at Microsoft, I bought a car through the Micronews. It really did give me a higher level of confidence knowing that, at a minimum, I knew where the seller worked and could find him if I needed to!

Some of the specific advantages touted by Microsoft include:

(1) Control over who sees your ads based on your Messenger buddy lists or other contact lists:

“Expo builds trust into your experience because it lets you control who will see your ads. You can keep it strictly among your Messenger contacts, your co-workers, or your school friends. Or you can throw it open to the world at large. The choice is yours. ”

(2) National and local search

“Unlike most other classified services, Expo allows you to search listings in your neighborhood or nationally, whichever you choose.”

(3) Integration with other MSN properties like MSN Spaces, Messenger, Windows Live Local Maps, and Driving directions