I just stumbled upon your gravity forms plugin and its exactly what I've been looking for. However, I couldn't seem to get it to work, it seems like the compatibility has been broken with Grafity Forms. Whenever I click on Prefill forms, the dropdown box to it doesn't seem to become "active", it can't be clicked.
Secondly when I save the form, the checkmark next to prefill isn't saved. Seems like it isn't saving the configuration.
Here is a quick screenshot: http://screencast.com/t/sZzsWoJy
Let me know if you need any other info from me to help resolve this.