I know this can be done with Adobe's InDesign - which is why I ask...

I have a series of numbered elements on a panel, and I'm curious if as I add new elements it could automatically number them correctly (1, 2, 3, 4, 5... when I add the next it automatically goes to 6).

Anyone know how?

I don't know if it can be done in Illustrator, but this can be done automatically in inDesign in Type>Bulleted and Numbered lists.

For those interested in the inDesign technique check out THIS (http://www.adobe.com/designcenter/video_workshop/index.html?id=vid0077) video.