WARNING: This is an experimental development build, it works, but use it with a grain of salt.
So many of you were probably already bugged to find the 2.5 interface completely different, but on top of that, it doesn't yet support YafaRay! So using the files below, we can make a temporary fix and use Yafaray in 2.53.
Note: I didn't make these scripts, I can't find the original author, but this is from yafaray.org
1. Download these two files:
Script A- http://dl.dropbox.com/u/9973564/YafaRay ... _win32.zip
Script B- http://dl.dropbox.com/u/9973564/Kerbox- ... aef6a6.zip
2. Navigate to C:\Program Files\Blender Foundation\Blender\2.53\scripts\addons
--Linux users go to something like /usr/share/Blender/Scripts/addons? correct me if I'm wrong, I can't really verify this at the moment.
3. Create a new folder called 'Yafaray'
4. Extract Script A into the yafaray folder.
You should get something like this:
5. Repeat with Script B, this time you will get a folder, move everything from that folder into the folder you are in now.
6. You should end up with a window that looks like this:
7. At this point, all you need to do is open blender. Now in the bottom left of any window, you will see an icon. Click that icon, and go to user preferences.
8.From there, go to Add-Ons and enable Yafaray, under renderers.
9. Now that Yafaray is enabled, on your top menu bar, where it says 'Blender Render', click it and choose 'Yafaray Render'.
You can now see that where your normal properties settings would be...
You see YafaRay Settings! Now pressing F12 will render in YafaRay, Happy Blendering, folks!