short answer: no
Long answer, quoting from a mail to someone else:
Well, I can tell you that it assumes a POSIX system, both in available utilities and system calls, So you'd need to use cygwin or something like that. (Perhaps you already are for git, I think git also assumes a POSIX system.) So you need a Haskell that can target that. What this page refers to as "GHC-Cygwin": http://www.haskell.org/ghc/docs/6.6/html/building/platforms.html I don't know where to get one. Did find this: http://copilotco.com/mail-archives/haskell-cafe.2007/msg00824.html
(There are probably also still some places where it assumes / as a path separator, although I fixed some. Probably almost all are fixed now.)
FWIW, git-annex works fine on OS X and other fine proprietary unixen. ;P --Joey
Alternatively, windows versions of these functions could be found, which are all the ones that need POSIX, I think. A fair amount of this, the stuff to do with signals and users, could be empty stubs in windows. The file manipulation, particularly symlinks, would probably be the main challenge.
addSignal blockSignals changeWorkingDirectory createLink createSymbolicLink emptySignalSet executeFile fileMode fileSize forkProcess getAnyProcessStatus getEffectiveUserID getEnvDefault getFileStatus getProcessID getProcessStatus getSignalMask getSymbolicLinkStatus getUserEntryForID getUserEntryForName groupWriteMode homeDirectory installHandler intersectFileModes isRegularFile isSymbolicLink modificationTime otherWriteMode ownerWriteMode readSymbolicLink setEnv setFileMode setSignalMask sigCHLD sigINT unionFileModes