Thanks to the iPhone 3G's purportedly sorry battery life, we think the must-have accessories for the iPhone 3G are arguably (1) an extra charging cable, and (2) a battery extender. We've mentioned the Kensington Mini Battery Extender before, but I personally find it adds a little too much length to the iPhone 3G.
MStation, which released the Mophie juice pack battery extender for the first-generation iPhone last December, has just announced its second version of the Mophie just for the iPhone 3G.
Dubbed the Mophie juice pack 3G, this portable charging dock even comes "precharged" right from the package, which is a rarity with these battery extenders. It has the same ergonomic and comfort-grip case as the original, and though it adds a little bit of bulk to the iPhone 3G, it doesn't seem too bad. Besides, mStation promises an additional 350 hours of standby time, 6 hours of talk time on 3G, 12 hours of talk time on regular 2G, 6 hours of Internet use on 3G, 8 hours of video playback, or 28 hours of audio playback. Of course, your mileage may vary depending on your daily usage, but that doesn't sound too bad at all.
The Mophie juice pack has a four-LED "charge status" indicator and even connects to your computer via a USB passthrough, which you can't do with the Kensington battery extender.
The Mophie juice pack 3G will be available in September for $99.95 retail.