It puts all these groups into the Unnamed People album, where you can easily add a name tag to a set of faces by clicking Add a name and typing the persons name.

Make sure youre signed into your Google account so names you type will autocomplete with your Google contacts.When a user adds a name tag, all pictures that the program has identified as that person are automatically added to a new album named after them. As Picasa scans more faces, it will suggest images that it thinks fit the profile of people already in your albums. There are also features you can use the tags with that let you do things like make movie clips and collages.