I attended a short Scrum seminar today. Mostly an introduction to Scrum. I have never personally worked with Scrum, but I have colleagues who (almost) work with it.
One of the problems with Scrum is that it is not so easy to implement. It is not just the development department that needs to accept it, it must also be accepted higher up in the chain: product owner. The product owner must make time to get involved in the development with respect to features and prioritization. And this work is not something you can do one time per 6 month period, it must be done at each "sprint" (usually about 2-4 weeks).
One thing a learned from the seminar that I did not know was the positive side effect of Scrum: team spirit. It can be used as a motivational tools to get more out of developers!
Here is what Wikipedia says about Scrum