I literally signed off today on an image of mine that will be used in "Pathways to Astronomy" soon to be published by McGraw-Hill....I'd had a number of images before that which have been used in print elsewhere.
Sadly human nature is such that many can and do rip-off images (and intellectual property in general)...and lots of luck pursuing the Wong Foo King or Li Ying Cow publishing company (Taipei Inc,) for using your work.
Hence, my thoughts are if you think you may get lucky and obtain commercial interest in your work, don't make it easy for someone to steal it.
Once uploaded, there is no taking it back.
But, if you have absolutely have no concerns about your data being plagiarized or appearing without due credit, etc....welll...go right ahead.
