It would be super useful to have the option to open the follow up page for an embedded, iframed, or standard Marketo form in a new tab similar to the hyperlink Target dropdown menu in the WYSIWYG.
I've had a number of cases about this since Forms 2.0 was released.
One could use the Forms 2.0 API: http://developers.marketo.com/documentation/websites/forms-2-0/ to change the form's target attribute: http://www.w3schools.com/tags/att_form_target.asp
However, most customers I've recommended this to can't go that route because they don't want to lose the progressive profiling and prefill capability by embedding the form code. The conflict is that customers want to use an iframed form to take advantage of prefill and progressive profiling, but if they do the followup page opens inside the iframe. If they try to use the Forms 2.0 API to alter the form's target, then the progressive profiling and prefill doesn't work.