...A photograph of an individual in a public place is by definition not private information. What occurs in public is public...
...I'd imagine we'll be pretty safe...
Safe?
...as long as we don't accept seriously substandard photographs of celebrities, if it's similar in appearance...
Copyright infringement case law allow damages for publishing look-alike pictures, even if only in design, layout, or theme - not just outright "copies".
My challenge is who takes responsibility? Wikipedia, or the submitter, or the photographer?
...We want free photos, but we don't want free photos likely to get us into a whole heap of trouble...
Therein lies the rub.
"Getting into trouble" is not up to us, it's up to anyone who accosts us or sues us. We might prevail, or not.
"Doing the right thing" is up to us, regardless.