Powce was successfully sold to Six Apart. She has a proven track record of building things that people like and want to use, but you can't win them all.
Sure. They went straight to work on something similar that Six Apart was cooking up. But, there have been many amazing products shutdown over the years due to talent acquisitions.
Pownce ultimately would have been forced to shutdown due to the popularity of Twitter and Facebook I think, but that doesn't mean that it itself wasn't a good product.