IMO, software has cycles. Early systems have lot's of known issues that can be quickly fixed. Then mid cycle have little or nothing minor wrong and so you tackle one or more major issues. Then your back to having lot's of little bugs to fix. Microsoft has discovered you can sell both parts of the cycle both new features aka Vista and then bug fixes Windows 7. But, when people talk about the minimum valuable product what they really mean is the smallest cycle where you get something people will pay for at the end.

The secret is to setup your cycles so you make enough money to keep going and or know when to let a product keep without investing in the next cycle. EX: Windows ME. Or Coke with sugar, new Coke with corn syrup, Classic Coca-Cola with corn syrup. http://en.wikipedia.org/wiki/Coca-Cola