If you always wanted to know “What kind of data does this crappy facebook-iphone-app send all the time?” then this might be the right way to find out:
http://blog.jerodsanto.net/2009/06/sniff-your-iphones-network-traffic/
Basically you have to install Paros, a proxy to sniff your iPhone traffic. Then you have to set the URL of your local mac-ip on the iPhone, that’s it.
Happy sniffing