I had an interesting revelation yesterday: there are several things in common between open source software (philosophy) and agile development methods (at least Scrum). Of course OSS in itself is pretty agile, but more as a by-product of the field rather than something by design.
Transparency. In both the aim is to be open about things. In OSS the big thing is of course that the work artifact is there for all to see and usually developers are pretty open about what they plan. In agile software development the aim is to have everyone in the project to be able to know where the project is at at any given time. In Scrum there is a host of things with this purpose: the Daily Scrums, the Burndown charts, the reviews, the whole aim of having the team sit near each other and so on.
Trust. OSS creates this by default - anyone can check the product. No hidden agendas. In Scrum trust is both delivered and expected in many layers: for the teams to work well, the managers need to trust the teams enough to give them the power to make decisions, in return they should receive accurate information on where the project is. This creates mutual trust. Teams within themselves should also trust each member, otherwise performance will suffer.
Self-organization. In open-source development people can pick and choose what they want to do and in what order. In Scrum this sort of self-organizing is also a core idea, the management should not intefere with day-to-day work. Of course commercial development usually has more constraints in what can be done, but still, to get best possible performance it's better to let the team decide on the minor details regarding job organization. Micro-management isn't very effective.
These are all, as can be seen, inter-connected. It's harder to have one without the other. And they are all very beneficial.
On top of this, the open-source has one huge advantage for Scrum teams: since the source code is freely modifyable teams and companies can modify them to fit their needs. In Scrum the idea of modifying the process, methods and tools to fit the current project as well as possible is a core idea.