The R13A release readme has this note:
OTP-7846 There will no longer be any warnings for list comprehensions without generators, as such list comprehension have turned out to be useful.
I found it curious what kind of use or possible abuse one could have for this. So I set out for some googling and found this discussion on erlang-questions about using list comprehensions without a generator.
Thought I would share it with the blargosphere.