How do i create the properties count on top of map?

Would like to create site with similar functionality tohttp://www.realtysouth.com/consumer/listing/ListingSearch.aspx?SearchType=map&ListingType=1&ListingSearchID=&RECoJumpSearchID=&action=&defaultlevel=

for our site

www.mls.ca

How do i create the properties count on top of map?
Im assuming that i have to call a web service to return me the count and pinpoints. How do i search for properties in SQL db that are in selected map area?

thanks

steph

[580 byte] By [sviau] at [2007-12-27]