I've been looking also but haven't seen anything. Incase had a dual charger but with their new iPad charger, it's just a single (iPad only, but it does charge at 2.1 amps, which is necessary for the iPad).
Well it didn't take long (less than nine hours) to contradict myself. I was looking at screen protectors over at zagg.com since some folks in the forum here have had good experiences. Low & behold they actually have a dual USB charger combined with a stand-by battery. One of the USB ports is speced to charge the iPad: "Charges the iPad at the same rate the iPad wall charger charges the iPad," according to the claims on their page.
See the ZAGGsparq 2.0 for more info. If this really can charge two different USB devices, one being the iPad, it seems like a winner. (Plus it's worldwide: 100-240 VAC @ 50/60 Hz.)
Thanks for input people! Zagg looks pretty good, but a but pricy perhaps (shipping to Norway is expensive). Lets see what the next couple of weeks will bring us of third party products.