Can you explain in just a bit more detail how you did this? This sounds really neat. I faced a problem like this a while ago, but luckily the file was still open in emacs (and in an emacs buffer), so I just re-wrote it back to disk.
This was a linux laptop. I immediately powered off and booted with a live CD. To be honest I'm not sure exactly what I did next. I might have just done "less -f /dev/sda5". I think what I actually did was make an image of the partition using dd to an external drive so I would be able to recover the file at leisure. Trying now, it seems that vim won't open a /dev block device directly, but an image is just a regular file.
Edit: it's possible I used "less", I can't remember.