You'll find it there:
ftp://downloads.ta3d.org/binaries/windows/dev/0.6
What does it brings compared to previous alpha ? Lots of things but mainly:
- OpenGL is loaded at runtime and no more linked against the program (fixes lots of bugs on all of platforms)
- Translations have been updated/improved
- There is a window to access the online mod repository (it's still Work In Progress so don't expect it to work without bugs)
- Lua AI API has been improved and includes more functions required by AI coders
- some new console commands for Lua debugging (mission and AI scripts)
- String code replaced with libYuni Strings
- lots of bug fixes everywhere