Make your BuddyPress network mobile optimized. BuddyMobile is free Mobile theme for BuddyPress sites. It is optimized for viewing on iPhone, iPod touch and also works on Android and some Blackberry devices.
BuddyMobile is most famous BuddyPress mobile theme. Just install and activate and it will automatically detect mobile devices and uses Mobile theme. It provides Options to switch between desktop and mobile theme display. You have two different theme styles to choose from and much more. See more of its screenshots or just give it a try.