Jon Rowett has discoverd FIT. I’ll be talking about FIT at the London .NET user goup tonight. It is really easy for teams that start doing TDD to forget that acceptance/customer tests are part of the whole picture. It tends to lead to programmer/unit tests that do not test units but end-t-end calls.
There is some examples good of using FIT in James NewKirk’s Microsoft Press book. It may be a good place to start for people who want to know how FIT fits in with TDD.