I have a friend who had a 40+ inch rear projection TV(not a modern LCD/plasma but one of those much larger ones), a couple of very large wood cabinet speakers(probably at least 3.5-4x1x1 feet) and a small mini fridge(still filled with food) all stolen, during daytime hours, from a 20-25 unit multi-story apartment.
Anecdotal I know, but I wouldn't assume most people are terribly attentive.