IMHO the best logos are "previous" by Thomas (rc2) (second place are by Yiannis) - they are simple, clean and readable (especially *nix logo).
Don't offence, but...
I don't like "proposal" logos by Takeshi Miya becouse, imho, they are overloaded by "shadow" effect and they have strange two-color background (plastic-like effect?).
I don't like "actual" logos by Thomas becouse, imho, colors are bad and "hurts eyes".