WordPress MU

would this plugin allow me to add features that allow users to add points/markers on a map? The points/markers will be similar to a classifieds ad.

You may want to take a look at gMaps and see if this is something you can use to achieve what you are looking for:

http://thepremiumpress.com/products/gmaps/

However, be warned, we are a commercial company offering paid subscription based support with our products, but they are entirely GPL based, which is why we are also featured on the WordPress Commercial Theme Company section - http://wordpress.org/extend/themes/commercial/

Please feel free to drop by our website and ask us anything you like, or visit us at BuddyPress.org - http://buddypress.org/community/members/thepremiumpress/