I propose we establish a policy that PD confirmation must be sought for all images obtained from US government websites.
Only material actually produced by US federal government employees in the course of their work is automatically PD. Often government websites also contain commercial stock photography and other contract works which we have no right to use. US Federal government websites are among the most responsive on the internet, so obtaining such permission should not be an issue.
There is usually an opportunity to apply common sense: If it looks like stock photography it probably is, and we should ask. Very few government agencies actually produce their own publication grade images. However, there are a number of well meaning wikipedians who have very wishful ideas of what we can use... If we ask them to apply common sense we get Alanis Morrissette's Ironic uploaded.
I've spent a lot of time thinking about this, and I think the best course of action would be for use to make a strong statement that we *always* prefer works made by wikimedia project participants. If we must choose between a work with free licensing and one made by a wikipedian we should always replace the free work with the wikipedians work unless the outside work is clearly better. If there is any possible doubt in the copyright the work should be replaced by a work from one of our users. We should avoid making outside works featured images.
The wikimedia projects already have a sizable and growing base of photographers, illustrators, and musicians. It is completely reasonable to believe that we can meet our own media needs, excluding specific historical works that we wish to comment on.
This position, along with some additional point guidelines (like contacting US federal agencies to confirm PD status), should largely address these copyright problems over the long term.
Some example which I have confirmed to be copyvio: http://commons.wikimedia.org/wiki/Image:Hiker_drinking_water.jpg http://commons.wikimedia.org/wiki/Image:Woman_in_Lotus_pose.jpg http://commons.wikimedia.org/wiki/Image:Girl_with_braces_in_for_checkup.jpg http://commons.wikimedia.org/wiki/Image:Hand_holding_a_tablet.jpg http://commons.wikimedia.org/wiki/Image:Bicycle_rider_with_helmet.jpg http://commons.wikimedia.org/wiki/Image:Girl_with_braces_in_for_checkup.jpg http://commons.wikimedia.org/wiki/Image:Physical_therapy_exercise.jpg http://commons.wikimedia.org/wiki/Image:Family_playing_wiffleball.jpg http://commons.wikimedia.org/wiki/Image:Old_man_reading_in_library.jpg http://commons.wikimedia.org/wiki/Image:Ambulance_in_action.jpg http://commons.wikimedia.org/wiki/Image:Old_couple_reading.jpg
Once en is writable again, I can begin pulling these from articles so they can be deleted.