Double, and triple checked. You can reproduce this yourself. I'm using a MacBook Pro for this. 1. Plug your MBP to wired ethernet - you have one of these in yo

Double, and triple checked. You can reproduce this yourself. I'm using a MacBook Pro for this. 1. Plug your MBP to wired ethernet - you have one of these in your home, right? 2. Open an ad-hoc network in your MBP, and share Internet access via that ad-hoc network. 3. Connect your iPhone to your MBP's ad-hoc network, now it should be able to access the Internet via your MBP. 4. Install and fire up Wireshark in your MBP - make sure to read the instructions or otherwise it can't capture packets. 5. Get Wireshark to capture packets on the ad-hoc Wifi interface. 6. Filter out the HTTP packets going to *.foursquare.com by adding the filter 'http.host contains "foursquare"' 7. Fire up Foursquare on your iPhone, login if you haven't already 8. Boom, you've just sent your password in plain text, over the Internet.