When you post new blog entries, or upload Flickr photos and YouTube videos, your Mugshot friends will see those updates on their Mugshot pages and Stackers. You'll also get those updates, to see how they are displayed to friends. These kinds of updates are visible to anyone, just like on the sites they come from.

Updates from external accounts with private information, like Facebook, will only be visible to the account owner. Private updates are indicated by a lock icon.