Yeah, I usually end up monkeying around with the code of whatever lightbox script I'm using to insert the attribution link but it is far from ideal.

If you think about it, this is an opportunity for WordPress to standardize polite gratitude.

It would be even better if they also took the opportunity to standardize unobtrusive DCMA takedown request links for every image, a pretty important precaution you or your users upload images that you believe to be CC but may, in fact, not be.