Somewhat confusing in their differences, Griffin Technology's new 2008 versions of PowerDuo ($40) and PowerDuo Universal ($35) have arrived, both boasting full charging compatibility with the iPod and iPhone. Whereas PowerDuo Universal is a two-piece kit with a USB wall charger and USB car charger, neither bundled with cables -- you provide them yourself -- the standard PowerDuo is a three-piece kit with a wall charger, car charger, and USB-to-iPod…
