Originally downloaded February 3, 2007. This is the coolest thing... Development just began in September 2006, but it appears to be proceeding rapidly, and I gather the developer is getting lots of encouragement through donations and such. I never became proficient in Vi when I worked in Unix routinely... I always used the much easier (but less powerful) Pico. But apparently this developer is working on a Cocoa InputManager plugin that basically lets you edit with Vi in any text view in a Cocoa application. This means, use Vi in Smultron, or in TextEdit, or in Safari, or in Xcode, or in DevonThink... man, this might just be the incentive I need to learn Vi. The developer's page has a list of all the Vi commands currently supported, and there are tons of them!
Version as tested: 0.3.1.
