It's especially bad when modules are extremely likely to be used together, like Control.Monad.State & FRef, or Data.Map & the Prelude. You end up being required to import one or the other qualified.
I think in the case of State vs. FRef a simple solution is to make two modules: FRef, which uses "get" and "set" and "modify" naturally, and FRef.State which defines State equivalents without polluting the namespace. Then if you're working with pure functions you can import FRef and use the natural names, and when you're using the State monad you can import FRef.State and get the State definitions that dont interfere with the standard "get" and "modify" names. In the rare case (I think, am I wrong?) where you use both State and FRef "modify" and "get" definitions in the same file, you can import the one you use less off qualified...
-- ryan
Tim Newsham http://www.thenewsh.com/~newsham/