does anyone know if you can do a scripted email that includes the results of a saved search? use case: sending overdue invoices every 7 days as part of a workflow email that includes the results of a search

Yes, but this can be done on the saved search itself. No need for scripting or workflows.

hmm

Or you simple use a map/reduce to parse the results and email (if you need a customized template, etc).

I think this is the route we will end up taking

That's what I do for a handful of very specific and customized emails. works well.