Here are Brian's success indicators for Open Source projects, from his Apache: When the Code Just isn’t Enough ApacheCon session.

A Successful Open Source project:

• Has a healthy community

• Makes decisions by consensus

• Can survive people being hit by a (rarely real, but often virtual) bus

• Can survive poisonous people

• Doesn't let perfect, be the enemy of good

• Has a mission statement

• Documents both software and processes

There's much more to his presentation, but this list is the best part for me.