It has taken a while, but version 1.5_01_E is out.
Fixed are the sunset lag spikes and fancy clouds rendering on some nVidia cards.
Unfortunately the most interesting new features did not make it in the E release.
Currently OptiFog has three development branches:
A. Anisotropic Filtering and Full Screen Antialiasing using texture atlas
Adds AF and FSAA using the default Minecraft texture atlas.
Not quite working, some color bleeding is still visible in far objects. May need some shader support to really work.
B. Anisotropic Filtering and Full Screen Antialiasing using separate textures
This one is in development. The performance may be problematic, still have to be tested. If it works Minecraft will finally look nice.
C. Background chunk loading
Loads chunks on a separate thread.
On dual-core CPU-s it uses the second core for loading chunks while the first one renders. Chunk loading should not cause lag spikes, even with integrated graphics.
This branch is already working, but not yet deliverable. Mod compatibility may be problematic, because more class files are changed.