Yes.  If you would like to publish a song to a specific group and not publicly ("Everyone" in SongSilo), you simply choose which group of people you would like to publish to within the "My Silo" page as seen in this image:


Once you choose the group, click publish.  Only individuals in that group will be able to see your latest track on the connect page and on your wall.

Note:  You can create new groups on your friends page and add your friends to them by dragging their profile image into the desired group.  Click at the top of the page to view your friends & manage/create groups.