9 pandas on a green canvas.
Adam Rifkin stashed this in Pandas!
Ah, but Tineye will....
Tineye points to a bunch of hi5 and photo bucket pages. I'm certain none of those are the origin.
I haven't had time to dig deep, but the answer's in there somewhere. I got distracted by the first or second link.
That's the nature of the Intewebthingy. It's so non-linear.
I'm not convinced that that page is the origin -- its image is hosted at Acidcow, another photo bucket-like service.
However, the wiresmash page does have some sweet panda art on it, so thank you for sharing!