Just Mobile has come up with an interesting and smart way to diversify its iPod and iPhone battery lineup in Gum Plus ($70), a repackaging of the same high-capacity 4400mAh battery from its earlier Gum Pro into a nicer-looking but larger enclosure. Those looking for a comparative bargain can still go with the $60 Pro, but Plus includes mini-USB and iPod/iPhone cables, a carrying case, and a MacBook-style aluminum enclosure with Apple-like power…
