This summer Maarten Lankhorst did some basic work on win64 support but for the rest no work has been done it for a long time. I'm not sure what Maarten exactly did but but there is a lot of work to be done before it will run even a basic app.
I think we still have the problem that gcc doesn't support the calling convention Win64 uses, so we can't compile a Wine that is compatible with Win64 apps.
That may be fixed in gcc already though. I haven't checked since some time.