Just that I've never heard of it

*edit*
Ah, a little research explains to me that it's an implementation of PGP. Neat.

For my purposes, though, I think 7-Zip is the kind of lightweight and easy to use tool that I'm going to need. I'll be offering this as a suggestion to a couple people sending files back and forth, and I think the simplest solution is best (even though that phrase is never actually true in security ).

I'll try all of these solutions and see which ones I can best explain to non-technical people. Thanks!