One of our business analysts caught me being too serious today about the definition of "Done" and sent me this:
"The USDA highly recommends use of a meat thermometer to determine doneness…"

Just like a thermometer, we have to have some way of know when we're done. Chicken is done at 160 degrees... software is done when it has met the organizational standards for quality and readiness.
What are your organizational standards for "Done"?