InfoPath Dev

I need to present the user with a dialog box whenever a particular repeating section is created. The dialog box will ask for a name or description of the new section, once the user has input the name the repeating section (or a field within it) is populated with this name.

Anyone ever done this kind of thing before?

I haven't heard of a way that you can take input in a dialog box, but there are several that provide "Yes", "No", "Cancel" functionality.

I think you will want to provide a place within the form that allows you to name the new section. Why can't you just make the "field within the repeating section" editable? If you want to make sure that the users enter a name you could pop a dialog upon the insertion of a new row, or just use data validation that will outline the field in red while it is still blank.