Let me offer a few case studies of cases in which a company has donated images and then asked to have them deleted. In one case we successfully kept the images, in two other cases we didn't...

Case #1: Pearson Scott Foresman (educational publishing company)
Donated: A couple thousand non-digitized original illustrations, in a box. http://commons.wikimedia.org/wiki/Category:PD-ScottForesman
Situation: Three years after the donation, their lawyers sent us a DMCA request to remove all the images. Luckily, we saved the original letter that accompanied the box. The letter included a statement that the donation was authorized by Pearson Scott Foresman President, Paul McFall. We faxed the letter to their lawyers and they withdrew the DMCA request.
Outcome: Images kept

Case #2: People for the Ethical Treatment of Animals (PETA)
Donated: All the images from their website (including advertizing materials featuring celebrities)
Situation: A community member contacted PETA asking for permission to license certain materials. The representative who answered the email stated (incorrectly) that everything on the PETA website was free for use without restriction (i.e. public domain). The email was stored in OTRS and dozens of images from the PETA website were then transferred to commons. Due to the high commercial value of some of the images (esp. featuring celebrities) someone else contacted PETA asking for clarification on the licensing terms. The 2nd representative talked to PETA's legal department and determined that they didn't own most of the images in question.
Outcome: Images deleted

Case #3: Cafe Magazine
Donated: Dozens of images of celebrities by posting to Flickr under a free license
Situation: A couple community members imported the images from Flickr and had them Flickr-reviewed. A year or so later a representative from the Magazine asked to have them deleted. After much discussion it was established that Cafe Magazine didn't own the images, but only licensed them for publication. The copyrights were actually held by various photographers and agencies.
Outcome: Images deleted

Lessons learned:
1. Having the images posted to Flickr isn't always adequate
2. Having an email in OTRS isn't always adequate
3. Don't rely on the word of the PR rep; ask for higher-level authorization if possible
4. Save everything related to the donation (or forward to OTRS)
5. Cheesecake images of celebrities are never free

Ryan Kaldari