Nick, ask GoDaddy to whitelist your domain on mod_security. I've been replying to other similar questions with the following:
There is a potential fix for 404 errors --> have your hosting provider whitelist your domain on mod_security.
I was getting 404 errors using the diagnostic URL at the bottom of the Social-Connect config page in WP and when when using Y!, Google, and WP.com.
For me, Y!/G/WP.com would authenticate properly and pass the user back to my web site where they then would get a 404 error. I know this because the 404 page URL would have all the data from the third party including first name, last name, and email. You can see if this is the case for you by highlighting all text in the URL and pasting into a text document.
My hosting company is Host Gator. I use WP 3.2.1 and Social Connect 0.7.