State of parallel GC?

I seem to recall reading in a GHC status report that there was some work going on with parallel garbage-collection. Looking at 6.8.1, it seems pretty clear that it didn't make it. Is there any update about where things are on that front? It isn't an immediately pressing need a Bluespec, but we do get asked every once in a while about parallelizing the Bluespec compiler. One of the technical reasons we're holding off on that front is that it wouldn't win as much as people expect (because garbage collection is usually a decent fraction of a typical run), so we'd be interested if the state-of-play in that area changed. Thanks, - Ravi