It's Michael Kors. I just saw the bright green version of it in my March Elle
michaelkors.com

Luna, excuse my ignorance, but may you happen to ID this bag too?
(picture is from the model's streetstyle forum, courtesy of celebcity)
I checked the text and the picture is from Fendi Spring 2008.
http://www.thefashionspot.com/forums/f89/showpost.php?p=4025765&postcount=8034
