This is good news, the Wellcome Trust have just launched the Wellcome Images website, where a load of its images have been released under Creative Commons licenses (BY-NC and BY-NC-ND) - see their announcement and coverage on the Creative Commons blog.
This is significant for two reasons. One, because they are one of the first major cultural institutions to endorse the Creative Commons licenses and philosophy. And two, because Wellcome Trust have lots of money and use some of it to fund web projects from other institutions, which will now be more likely to also use Creative Commons licenses.
I'd be interested to see how the images on the Wellcome Images site will be used. They won't qualify for Wikipedia usage, unfortunately, but there may be other sites who will find a usage for them.