iPhone/iPad Guitar Jack

I noticed this came out today and was wondering how it could be used for djing.

http://www.sonomawireworks.com/guitarjack/

It seems everyone has been trying to use iPads and to a lesser extent iPhones to enhance there sets. I'm not the best when it comes to jacks but this seems like it could be useful to some of us if only I could believe up a good way to use it. This does lead me to believe that other types of in/out jacks would be possible. I mean wouldn't it be awesome if there was an "Audio 2" type App and you just had to get an accessory like this and boom your phone is now your sound card. I know theres a lot more involved than that but it's mind blowing where technology is going and at such a rate. Just thought I'd share with you all.