FLOSS that implements badging and contextual menu in Snow Leopard's Finder

Apparently with Snow 开发者_开发技巧Leopard, due to rewrite of Finder in Cocoa and removal of Contextual Menu Plugins, it is no longer trivial to do either badging nor contextual menus, however Dropbox seems to both add a contextual menu in the managed folder, and add status badges.

Is there an open source project that managed to solve this problem?

It's been years since this question was asked, but here's (almost) exactly what you were asking for: FLOSS that implements badging and contextual menus, but only for Lion and Mountain Lion (but I'm sure it wouldn't be too difficult to adapt it for Snow Leopard if still needed).

Liferay Nativity provides a scripting bundle that will swizzle the relevant Finder methods and a Java client for setting the icons and context menus. It also includes equivalent projects for Windows and Linux.

The project is open source under LGPL, so feel free to contribute any bug fixes or improvements!

I think Dropbox may have reverse engineered Finder if I recall their comments at PyCon. The full video is online and the slide is 16 minutes in.

you will need to inject code into the Finder process and override objective C methods in the Finder process. refer How to Write OS X Finder plugin post.