Currently we do not support that. Would you want the user to fill out the form, save it and then submit it? Or they fill it out, partially submit, then come back later complete filling and submit the rest? Can you provide more detail on your use case?
Thank you, Randy for getting back to me. The second (partically submitting and returning to do the rest) is what we want. It's for trainers to choose from a list of presentations by adding their name to the box for trainer and come back to add how many attended, for instance.
We just added the ability to distribute your form as a fillable PDF form and have all of the data submitted back to FormsCentral. Your respondents can save the PDF form locally, fill it out, save, come back later to finish and then submit the data. I wrote up a forum post that explains it in more detail: http://forums.adobe.com/thread/994199
Please give it a try and send us your feedback on it. I think it will likely address your use case.