I just love that picture!! If I knew how to save it for myself I'd use it as wallpaper...
But then again, the nannies at work would have heartfailure.
Right-click on the image, select the save image option in the context menu. For Firefox, that's "Save image as ...". Other browsers have similar options. (I don't know how to get the context menu on Macs. It's probably ctrl-click or something like that.)