What to do with old battery?

I took apart an old iPhone 3g, and I accidently punctured the battery. As i looked closer, it said do not puncture. What should I do with it?

Contact your local Staples, they usually have battery recycling bins, DO NOT THROW IN REGULAR GARBAGE

I don't know i would just throw it away. Or when you go to att for a new battery just give it to them.