I found this fantastic post from Tobias Meyer on the scrumdevelopment mailing list:

"There has been a lot of discussion on this list recently about what Scrum can and can't do, what it does or doesn't do, and how Lean can do things Scrum can't do, and so on. It is starting to feel like meaningless noise.

Scrum doesn't do anything. Nor does Lean. People do things.

In the end it doesn't matter what names you use for your processes, good people will do good work and continuously improve what they do. So much of the discussion around Lean versus Scrum (etc.) is about marketing hype, selling consulting and training services, and cornering the market with new name-brands. It is easy to confuse people new to this list about the nature of Scrum.

Scrum is not a methodology, it is not a process. It is a simple framework underpinned by some common sense principles. Scrum offers individuals and organizations the opportunity to continuously improve the way they work. It provides a space for people to behave like human beings, with trust, respect and passion. That's about it. But that is huge.

Scrum won't save you, it won't fix your organizational dysfunction, and it won't solve your interpersonal problems. Nor will Lean. Nor will XP. Nor will any new brand-name Agile "solution". So get over it -- and more importantly, get on with it. There is work to be done :]"