We started using scrum in my group this week and I'm already finding myself pushing aside work that I would normally sign up for in other groups. Scrum gives you to choice of being able to say "I did what I said I was going to do yesterday" or "I didn't." I want to always be able to say the former or have a good reason why not. Is "I was working with this other group" a good reason when the rest of your team is focused 100% on the thing? This is going to play hell with MS culture, but in a good way, imo.