A few months ago I left my jacket on a SFO bound plane - I had swapped with someone else so they could sleep and forgot to grab it before I got off the plane and went landslide.

I was able to talk to someone working at the luggage desk who went back on the plane right there and grabbed it for me (there was someone else that had forgotten her wallet on the same flight as me). I don't know if it's standard procedure, but it was awesome.

I don't recall any of my co-workers ever getting anything they left back once they've gone from the airport though. Usually just a pair of headphones or something like that.