From the Link: Calculating the True Price of Software by Robert Lefkowitz — Businesses have long viewed support and maintenance as essential components of software. Open source business models often focus on charging for support and customization. Is there an economic model that can demonstrate the true worth of a piece of software and the option for support, maintenance, and upgrades? Robert Lefkowitz argues that open source exposes the true value of software itself as, essentially, worth less in comparison to support and maintenance.
In an agile environment, all work done needs to be directly related to the needs of stakeholders. Stakeholders request or “pull” work from the team, and they do this by defining prioritized work packages. The team needs some way to know when they have completed a work package, so both work packages and iteration tasks need to have testable acceptance or success criteria. The team collaborates with the stakeholders to determine what needs to be done to successfully complete a work package.