We have developed a work around to the plugin conflict Gravity Forms currently has with the Wishlist Member plugin. We will be including this fix in the upcoming 1.3 release.
We do have a patch available for Gravity Forms v1.2+ that will fix this issue but we will only be releasing it on an as needed basis.
If you are running Gravity Forms v1.2+ and need to patch it so that it works with the Wishlist Member plugin, contact us via our Contact Us form and we will be glad to send it over to you.