Currently you can only distribute the form as a web form and not a PDF fillable form. Being able to save it as a PDF fillabe form is something we hope to provide very soon.
We just added the ability to distribute your form as a fillable PDF form and have all of the data submitted back to FormsCentral. I wrote up a forum post that explains it in more detail: http://forums.adobe.com/thread/994199
Give it a try and please send us your feedback on it.