This is the full-color version of the currently unofficial Linux logo. ("currently unofficial" means that there has been no paperwork and that Linus have'nt announced it yet).It was created by Larry Ewing, and is freely usable as long as you acknowledge Larry as the original artist.
Note that there are black-and-white versions of this are avaliable that scales down
to smaller sizes and are better for letterheads or whatever you want to use them for:
for the full range of logos take a look at => Larry's web-page.