I know this is an old topic but I just thought I'd add something because I tested some DV day-for-night stuff today. It's for a trailer that we intend to use to help get finance for a film set entirely at night. I had bright sunshine for most of the test, at around five-six pm, and I used a Sony DCR-VX2000E. I found that putting the inbuilt ND filter up to 2 and using its indoor white balance preset to get a blue tint, plus stopping down to F9.6, gave a really useful day-for-night look provided there's no sunlit patches in the shot whatsoever (which shouldn't be a problem on our trailer shoot). Even with sunlight in shot the effect is pretty good. Stopping right down to F11 gave a better night look but it lost almost all detail, even when I used a reflector and/or a light to try and kick up some highlights. F9.6 is every so slightly warm on flesh tones but if needs be we can correct that digitally. All in all, I was quite happy with the look.
James x