Quite a few people have used the original version of this image on their (non-commercial!) web sites (e.g. here). One of them blurred the bills in the background. I liked that, so I reworked the image a bit.
As per the Creative Common's copyright (Attribution, Noncommercial), feel free to use the image for non-commercial purposes (e.g. on a personal blog that does NOT contain advertisements) as long as you attribute it to me preferably be linking back to this image.
Contact me at firstname.lastname@example.org if you'd like to use it for anything commercial and we'll work out a licensing fee.