In the new promo (http://www.youtube.com/watch?v=5sBp58pzgLA) for iCan't Take It, they talk about a secret that could change iCarly forever (over exaggeration for intrigue's sake I'm sure). Then, they show a clip with Gibby telling Carly, "Tell us what you know" and then Mrs. Benson goes "Give into your anger."
There's this little bit with Freddie standing in front of Carly and Carly looks completely shocked. Mouth hanging open and everything. (See here: http://30.media.tumblr.com/tumblr_lrdjtkv0Gl1qcc187o1_500.gif) Maybe that's when Freddie tells her the secret?
So, what do you think the secret is?