Chris Butler, program manager at MSN, has posted a note on MSN Search's WebLog that the MSN Search Toolbar team has just released their first "add-in" for the toolbar. This one allows you to, "to view a three day forecast at a glance with one click." You'll find more add-ins as their released, here.
Butler also points out that the first partner services that uses the MSN Search Toolbar API has also just been released that allows users the ability to access files, folders and other material from your PC via any web accessible computer. More about FolderShare here. MSN is also making available a new compilation of add-ins for their desktop search application that allow user to search more file types than what comes pre-loaded with the desktop search app.