iPhone 4 Travel Battery Pack

We were using the Kensington Travel Batter Pack and Charger for our iPhone 3G, model number K33456US, but we discovered it did not work well with the iPhone 4. We later confirmed with Kensington that it is not compatible with iPhone 4. My wife really liked the travel charger, so this is a little disappointing. Does anyone have any recommendations for a good replacement for the Kensington for the iPhone 4? Compatibility with the iPad would also be good.

Thanks.