Ack! A year old thread, but just to clarify (since it's been revived anyway);

setfile -a V Makes the file invisible
setfile -a v Makes the file visible

The case [upper or lower] of the V is important.

I know that myself.

But I didn't want to install the Dev Tools to my netbook - 16GB ain't much enaugh to waste space - the .hidden doesn't work on SL, and I was to lacy to transfer files from my other hack, so I was looking into some non pay-software.
My only intention with that posting was to warn people about using this one....