Just recently picked up an iPad 4. Saw that it specifies "not charging" when plugged into the usb port. Saw that it is a common issue due to usb power. I have usb 3.0 ports on my desktop so I tried that and the same result. USB 3.0 is specified for up to 900 ma while 2.0 is 500ma. Course even that can change depending on a few things. Seems that the iPad wants up to 2.1 amps. So I searched for solution using dual usb ports like some external 2.5" laptop hard drives use. I found nothing which surprised me. If I can get 900ma x 2 ports (for 1.8 total amps) I am near the full charge spec for the iPad.
Such cables seem foreign but I found 2 of them. Most Y cables like this come with a mini usb at the end so these are unfortunately rare and more expensive (unless you want to solder your own which I suppose I could do too with my abundance of cables). http://www.shopaddonics.com/itemdesc.asp?ic=AA2USBPC http://www.newegg.com/Product/Product.aspx?Item=N82E16812161003
From here the lightning cord would simply plug into the female end. Anyone tried something like this? Result?