So further research is here ---
http://support.apple.com/kb/HT4049
per this document, i plugged the new ipad into the macbook, and run the system information
the numbers are here
Current available -- 500mA
Current required -- 500mA
Extra opertating Current -- 500mA
Thus i assume the minimum requirement is 1A.
So the total is 1A from the laptop.
The 10W charger is 5V at 2.1A
the 5W charger is 5V at 1A
I assume most after market ones cannot come close to 5V 1A as standard USB is 500mA. Luckily one of my car cigarette charge provides some power near 1A so it charges.
Let the search for cheap 3rd party 5V2A chargers (as backup) begin!!!!