If that's the cost of getting employees to stay late, it's a great investment.
Depends on why they're staying late.
During "crunch" times--usually a few months before shipping--a company I used to work for would bring in dinner. I know more than a few people who would hang out, let the company buy them dinner, and then go home shortly afterwards. These were usually the same people who would snag a half-dozen free sodas to take home on the way out (and, no, they weren't working from home).
I'd be more interested in things getting done. If people are staying late in order to get things done, that's great and I have no qualms about feeding them as a way of thanking them. But I've seen it turn into a "Hey, free food, let's stick around! Maybe we'll get a foosball game going after dinner. Look at us, we stayed at work 'til 11:00 playing ping-pong!"