There was a thread recently (here or on another site) where a guy was using some apartment bicycle rack as his personal storage rack for multiple bikes. Not directly relevant, but might be.

I'd leave a note and ask around to see if anyone knows who's bike it is. If you've got a spare unused extra wheel at home that would work for the bike you might offer it to the bike owner as a good will gesture in case the owner is finacially strapped at the moment.