More charging discoveries

Continued from Belkin 4 port USB hub / more iPhone charging experiences

I noticed a few more things about charging the iPad:

• charges with my MBP
• only charges when I plug it in first, if I plug in my iPhone first, my iPad doesn't charge!
• didn't charge when I plugged it into a HP desktop

I found this article by Apple, which explains everything:
http://support.apple.com/kb/HT4049

• some Apple computers and displays can supply up to 1100 mA (the normal is 500 mA)
• but they only supply this much to the first device that requests it

Looks like the iPad needs at least 1100 mA to charge, and with only 500 mA it displays "not charging" and only charges when sleeping.