Determining user's group

From: BarbaraC (bcherekjian_at_att.net)
Date: 03/17/04 

Date: Wed, 17 Mar 2004 09:00:36 -0800

How can I determine if the currently logged-in user
belongs to a particular group? I have a button on a form
that is used to release medical results and only
the "pathologist" group should be allow to use the
button. I would like to make it invisible if the user is
not a member of that group - or display a message if an
unauthorized user pressed the button.