There has long been plenty of interest in Stack Exchange clones. We even have a question cataloging them here.
I never thought much about why the Stack Exchange technology isn't for sale. Who knows, maybe the team just doesn't feel like selling their secret sauce.
Then I saw an interesting comment in an answer by ChrisF:
The team doesn't sell the system for "public" use any more. SE 1.0 was an attempt at that which failed.
What's the story behind this?