Thanks to the answer from John at avexdesign above as well as the link to the tutorial from SilenceIT, I have a couple more details in case anyone comes across this.
As of version 3.1, the line to edit is now line 60 in the controller.php file. As stated by avexdesigns, you must change ONLY the variables ‘$items’ that were added via the original tutorial to ‘$result’. There are many other $items in the file so make sure you do NOT find and replace all.
Also, per the SilenceIT tutorial, the if statement where you put all of this code in originally was:
} elseif ( $wpcf7_contact_form->mail() ) {
it is now:
if ( $result['mail_sent'] ){
Hope that helps!