The folks at TypeMock have written a page on how TypeMock makes your unit testing easier and more reliable.  Mock objects help when unit testing code that has dependencies (often external) that make SetUp/TearDown difficult.  Like the rest of XP (Agile), mocking is something you're probably going to have to "sell" to the decision makers.  Print out this article and give it to them.  Even if they don't go with TypeMock, at least they'll understand the reasoning behind mocks.