I installed a new template and a mod this morning from:
http://code.google.com/p/phpbb-iphone-style/
I have 0.8 with modifications currently installed.
It will auto detect if you are using a mobile browser and switch you to the iphone style. Please let me know if you have any problems with the template (even if you are using it from a non-mobile device). I'm hoping this provides an easier reading experience on phones.
I've tested it some and can confirm at least for the iPhone's Safari browser it auto-detects properly.
To disable the mobile style automatically switching when on a mobile device to go
http://www.sheffieldfamily.net/user-data.php
uncheck the checkbox at the bottom and then click Update Data.