I left an iPod and Bose headphones on the plane in DSM one December. It was the last flight of the day and somebody got an early Xmas. Had business cards in the case but no joy. If it wasn't the last flight of the day you have a chance, but if the cleaners find it, good luck.
Of course there are no numbers you can call anymore. I was on the phone right away to the eliite line, but DSM was outsourced then and even when I was able to get a number it was never answered.