Etiquette Tip of the Week: Let Them Eat...Lunch
If someone is eating lunch at his or her desk, do not loom and ask, "What's for lunch?" Do not interrupt the person and try to do business. Give them some space. Respect the lunch. It's a lot like when people are on the phone - do not hover in the door of their office or cubicle / veal fattening pen. Unless the building is on fire, do not interrupt them.
If you are the one eating lunch, be honest about your lunch time. If you have an hour, that doesn't mean go out and shop for an hour, then bring lunch back to your desk and begin to eat it after your lunch hour is over.