This article discusses estimation techniques for teams that are adopting Scrum. The authors recommend to use story points during the release planning phase, but initially to switch to hours to estimate tasks during the sprint planning. Then the team will gradually move to using story points to estimate complete stories that members will commit for in next sprint.

Mike Cohn wrote an interesting post where he discusses he allows or even encourages to estimate with story points as large as 20, 40, and 100. He explains that they are useful when you need first and not necessarily precise estimate of the general size of a new project being considered.

In this blog post, Mike Caspar gives a detailed answer to the question: What if your first scrum sprint ends up with zero story points completed?

In this blog post, Mike Treadway explains the technique of using story points for story estimation during agile planning sessions.