As reported by Marcus Thompson:
Again, Mark Jackson says Harrison Barnes is out first two games. When he returns, he will come off the bench.— Marcus Thompson (@gswscribe) October 29, 2013
There are no more details about his injury, apparently per his desire:
GSW say Barnes has to approve releasing details. Apparently he hasnt RT @nr1HBfan why they just don't tell the truth? It's insulting to fans— Marcus Thompson (@gswscribe) October 29, 2013
Chime in here for discussion of what this might mean going forward. In the short term, it probably means more Draymond Green. Which likely also means more Speights?