I know I'm arriving late to this topic, but here are two VFTs that have been living outside for about 9 months now. Living where I do (Charlotte, NC) I have the luxury of leaving them outside year round.
Reading this thread it seems to me that some people might be underestimating the cold tolerance of Dionaea. I'm in the same zone as Wilmington, which is rated at hitting about 15 degrees F at the lowest. The plants below have been outside on an elevated stand for the last week in sustained temps of 16-35 F. - quite a cold snap for us... about 15-20 degrees colder than average.
I know people in colder zones have to be more careful, as extended time below 15 degrees F. can kill VFTs, but when I see people rushing them inside when the temps get below 40 degrees I can't help thinking some people believe the VFT is much more fragile/tropical than it really is.
Wilmington's winter temps normally run in the 30-50 F. range, but there can be days or even weeks at a time when the night temps are below 20 degrees and the highs don't hit 40 - just like it is now. Wilmington is also not immune to snow. It's rare, but it does happen and sometimes they can get enough to complete bury VFTs for a few days. Admittedly, though, snow in this zone never stays on the ground for very long.
It's also very rare to have more than maybe a two-week stretch in the winter without at least a few days edging up toward 50ish degrees.
Anyway, here they are - they aren't pretty and photogenic; these are working plants! But they are doing very well, it seems, and haven't been killed by living in a tray of solid ice for the past week or so.