I have the latest versions of WP Super Cache (1.1), WPtouch (1.9.42), and WordPress 3.4.1. When I try to use them together, readers of my blog report that sometimes the desktop version shows on their mobile device (iPhone/Safari), and sometimes the mobile version shows on their desktop (e.g. Macbook Pro). Yes, I have the "WPTouch" plugin enabled in the super cache settings.
What causes this? Is super cache not respecting user agents? How can I fix it? Also, it appears to be a random problem, and switches back and forth between the two versions depending on the page you are viewing.