One warning: this component adds about 70 megs to your sql database size. No kidding. According to developer, this is necessary to accurately detete the hundreds of mobile devices. Unfortunately, this large size could prevent you from restoring your database. On my host, phpmyadmin has a 50 meg limit, so when my site when down, I couldn't restore the database. I finally removed all the mobilejoomla tables and the sql file went from 74 megs to 3.2 megs.
Since I only care about iphone, blackberry, and android devices, it would be nice if developer could create a config that would eliminate all the other tables and reduce the database size.
I highly recommend this product with one reservation: it can be difficult to get it working correctly depending on your server configuration. Luckily, the developer is VERY responsive and helpful.