The first time you run Peek-a-Boo, it will ask for authenticaton (an administrator name and password). The reason is that Peek-a-Boo’s child proces, PeekHelperB, needs permission to read information for all processes. This permission is also necessary for some of the process actions available from the Manage menu or the main window’s toolbar.
Since Peek-a-Boo accesses much of the same under-the-hood information as system tools such as top and ps, some people might wonder why they didn’t have to enter authentication information for those tools; but in fact, they did! When installing Mac OS X, the authentication provided also set up the permissions for the Darwin system tools.
You can verify this by using Terminal to see the permissions on these Darwin tools, and comparing with the permissions on PeekHelperB after you’ve provided authentication.
The authentication is used to set the permissions of PeekHelperB once and for all, so you shouldn’t have to re-authenticate every time you run Peek-a-Boo; only the first time, or when the helper is updated.