When will they have the Babylon theme fully ready for the SMF 2.0 Final version?
That was the previous default theme for SMF. I really liked that, much better than the new Curve default theme which seems some SMF/phpbb hybrid in appearance due to the less sharp "watercolor" look.
It wasn't the previous default theme- that was the Core theme, which was rather sharp and boxy. Babylon was the one before that again and only default in SMF 1.0(Core was default in SMF 1.1).The name came from one of its contributors was called BabylonKing. (or something similar, been a few years ago)
Curve:

Core:

Babylon:

Babylon isn't included in SMF 2.0 as Illori mentions - but Core is. Curve wasn't added in 2.0 either until RC2.
My board was first on xsorbit SMF 1.0.5 and the theme was Bablyon. Then I moved the board and upgraded it to the 1.1.x series, but still kept Babylon as my theme. I have screenshots of both Core and Babylon for my board but I'm reluctant to post them since my board is a private board.
I don't like the Curve theme at all with how blendy it is. It's really too bad there's no Babylon theme for SMF 2.0. The Core theme is better than Curve, but I still prefer Babylon. Any theme that was good enough to be a default theme at one point should still be an option, and not phased out by some marketing department.
I regret I switched over to SMF 2.0 before SMF 2.0 got a Babylon theme. I know the security is better, but the upgrade still feels like a downgrade due to the look.