Legally Speaking: When is a "license" really a sale?

Pamela Samuelson, "Legally Speaking: When is a 'license' really a sale?". Communications of the ACM, Vol. 52 No. 3, pp. 27-29 . (2009)
Abstract: 
Can you resell software even if the package says you can't? What are the implications for copyright law of the Quanta decision discussed in the November 2008 column?