I'm trying to solve a knotty problem with the network package on Windows at the moment:
http://trac.haskell.org/network/ticket/5
This looks innocuous - the getaddrinfo function isn't available - but it's proving tricky to actually fix. In addition, I'm worried that if I do fix it (i.e. I can get autoconf to notice that getaddrinfo is really present), that the next binary release of GHC or the Platform on Windows might accidentally not work on releases of Windows older than XP, depending on what kind of host the code is built on.