New Uses for Old Clipping Paths
http://studio.adobe.com/tips/tip.jsp?p=1&id=100771&xml=ind3kbvarnish

Blatner, David
Adobe
2004

Abstract:

No one enjoys drawing clipping paths (or, if they do, they rarely admit it in public). The transparency features in Adobe® InDesign® spare you the headaches of drawing clipping paths because the program honors background transparency in Adobe Photoshop® files. However, there are still times when a clipping path comes in handy, so don’t throw the Bézier out with the bathwater.