Back in the days of fxCop, (before we had to pay for code analysis in Team Developer) if you didn't like an error/warning, you could have your request to ignore said message in an external central file.
With the advent of Visual Studio Team Editions for Developers 2005, suppressions were stored as attributes in front of blocks of code. Look on the bright side we were told - now you could see your suppressions inline with your code, versioned alongside, etc. But we lost some things with this as well. Now if you were doing major code sweeps adding suppressions, you would be touching lots of files, creating some unnecessary code churn.
Another scenario may involve a given developer doing a sweep for localization, or security, compliance, etc. In fxCop, different developers could have different settings & suppression files.
Well, Visual Studio 2008 to the rescue. Code Analysis will now give us back this capability.
One of the little pet projects I'm working on is to take a code analysis pass, and cross reference that with a change set. The goal is to generate a report of obvious warnings related to the code I'm churning. We can't be perfect here as sometimes code analysis will return an error to a line of code you didn't change, but it is indirectly caused by that. The only way to truly get a clean report would be to do a code analysis before & after the checkin - that might be too much. But this would definitely be a great report for a build - to compare code analysis passes on previous builds.