What's the No. 1 must-have accessory for the new iPhone?

For power users who are fretting about the battery life on the new iPhone 3G, the Kensington Mini Battery Extender and Charger for iPod and iPhone 1G, 3G may be the solution to all your worries.

Powerplay: The iPhone 3G, extended edition. Sarah Tew/CNET Networks

With every step forward, there's often a step back, and in the case of the new iPhone 3G, it appears that battery life has taken a hit. Of course, the old disclaimer that your mileage may vary with use is in full effect, but the early consensus here in the CNET New York office is that if you're a road warrior/power user, you better have some backup juice on hand or you may be looking at a dead iPhone before day's end.

The solution: an extended battery. The sexiest one we could find was the $40 Kensington Mini Battery Extender and Charger for iPod and iPhone 1G, 3G. It basically doubles the battery life of the iPhone and allows you to charge both the extended battery and iPhone with its included retractable USB charging cable (in other words, no need to carry the iPhone's charger). As far as these things go, it's fairly compact and clips onto the bottom of the iPhone without being too obtrusive (however, you may have to remove your case to clip it on). I wish it also doubled as an A2DP stereo Bluetooth adapter, but that's another story.

Anyway, we suspect a lot of folks are going to be looking at batteries like this Kensington. Sure, when you connect it and talk on your iPhone, it looks pretty ridiculous, but on the upside, you'll have everybody thinking you're talking on some sort of super cordless phone rather than a cell phone.

Anybody else got a better battery extender option? Or is this it?

Check out CNET's full iPhone coverage here.