Highly doubt it. I've tried these 4 port chargers and even 2 port chargers for charging my Moto Droid which takes even less of a charge than the iPad and they usually don't work at all, overheat, or have some problem. If you link to the specific model you are looking at, I can tell you why or why it wouldn't work.
The iPad charger is a 2A (2000ma) charger for ONE device. Even though a lot of these devices, like this ([ame]http://www.amazon.com/Kensington-4-Port-USB-Charger-Mobile/dp/B001G5Z8Q4[/ame]) have a max output of 2A, most likely even if you only had the iPad plugged in it wouldn't be able to consistently draw 2A from the device...now if you plug in other devices to it, it get's even less of an output because technically if you have four devices plugged in it's 4x500a...
So even if one other device takes more than .01a to charge, the device immediately becomes inferior to the included OEM iPad charger.