I just installed the latest update for Fundraiser. I see you made some coding changes to the IPN routing in Class.gateway.php. However, you are still overriding the IPN setting in PayPal. Why do you do this. Can't you just let users set the IPN in PayPal (per your instructions) and let it go? By overriding the IPN address, you prevent me from using an IPN broadcaster.
For example. I setup an IPN broadcaster, and set my PayPal IPN settings to send messages to http://www.example.com/ipnbroadcaster.php. The broadcaster is then set to forward the message to WPMU Fundraiser (at the correct IPN) and also multiple other 3rd party systems. But in your class, you override this setting and tell PayPal to send the message to Fundraiser instead of my IPN broadcaster. This is a little frustrating, as I have to go in and edit your code whenever you do an update.
To fix this you need to stop sending to PayPal the "notify_url" form field. Just let PayPal handle the IPN notification as the user configures it.