I tend not to separate various flavours of testing in TDD. For me TDD is Test-Driven Development, not Unit Test-Driven Development. So my TDD practice combines unit tests, integration tests, functional and acceptance tests. This results in some components being covered by certain types of tests and others components being covered by other types of tests in a very pragmatic fashion.
I have asked a question about the relevance of this practice and the short answer was that in practice the separation is between fast/simple tests run automatically at every build and slow/complex tests run less often.
