v6: What is needed for release?

[Admins]

For the final release of v6 for Windows, Mac and Linux,
what should be done before the release:
- What bugs need a fix?
- What features or implementations need improvements, and what kind of improvements?

This discussion should be mainly about technically issues, not about server quality, payment options etc. Basicly the question is: what should be done before replacing the v5 download with the v6 download?