How can I charge a mobile phone on my MacBook Air (like I used to be able to)?

I wish I had a how to but I have a 2010 MBA upgraded to Lion. Connected my work phone, droid incredible, with the machine on and closed the lid and went to sleep and woke and the droid was charged. So it is possible just don't know where to tell you to go to make it happen. Also, meant to plug the MBA into power but forgot to connect the magsafe, so maybe try it without connecting the magsafe see if that was the trick.