I've run into a slight issue with this and I'll be dipped if I can figure it out. Seems some devices aren't being detected when hitting the site. For example, I have 4 users who all have iPhones. 3 of them continue to see the normal style and only one is being redirected to the mobile style. Getting the same issue with a user who has a Tilt. We're running 3.8 and the detect Windows CE and iPhone have been checked. I even went so far as to include CE, iPhone and Safari in the custom list. Same issue. Not sure if it's an issue with the individual phone, or with the installation. Any ideas?
Edit ---
I think we've fixed it. I added your modification to the portal template for the style and all my users are now seeing the forum in the mobile style. Don't know why that would have affected it, but my mobile users are a happy bunch now.