Purgatory: Is it Biblical? If not, what is its Origin?

I've heard of this concept before. I think it needs a full airing, given that it was raised in a recent post. To avoid stepping on the flow of the Universalism discussion, I ask it here:
- What is Purgatory?
- Where did it come from?
- Who's in charge of it?
- Where is it?
- Does Purgatory exist today?
- What qualifies one for purgatory?
- How and when is one release from Purgatory?
- Does the Bible teach it?
These and other questions can, and should, be asked of this subject. What is your understanding? CM