Sender Policy Framework for email is it a good idea?

I was looking at email authentication and ways to prevent spam when I found this site http://www.openspf.org/
that advocates something called sender policyy framework for people with their own domain. I found it because I ran a check on the security of the site I have, and one result was that the domain should take up spf to prevent spammers sending mail that looks like it came from my domain.

What do others think of sender policy framework??