Mylyn is a task oriented plugin that allows for example to assign a set of files to a task. Is there a Mylyn type plugin for Visual Studio?
i'm not aware of anything open source but i do know that team system is setup to support this type of workflow.
resharper might also have features you are looking for but, again, not foss
I asked that question to the VS.NET Development team in Teched 2008.
She said that they've notice about Mylyn, but are still looking on it. Task focusing plugin is not yet ready in VS.NET environment.
Not even close to mylyn, but here is an open source addin for visual studio that helps to assign a list of source files to a "session" (you could think of the session as a "task")
Mylyn is not currently supported in any Visual Studio distribution that I'm aware of. It is available only within the Eclipse IDE or as an Eclipse RCP application. The company that supports Mylyn, Tasktop, has a survey where you can specify which IDE you're using. If you choose Visual Studio you are effectively voting for Mylyn support for VS.
Vote for VS support: https://tasktop.com/support/survey/
David Shepherd, Tasktop Technologies
http://www.twitter.com/davidcshepherd