This page shows the release notes from 2006.
==2.1.8==
Release Date: 12/30/06
* More butterflies from grass
* Birds in the sky
* Fish in the water
* Made smoke particles lit by the surroundings
* Tweaked fog particle generation a bit for "mistier" fog (pretty weather required)
* Particles fade out when close to the screen to avoid blinking when a particle passes the player
Other fixes:
* New console command: "refresh". Rebuilds most display lists and textures. Use if your terrain starts looking weird.
* The spyglass works again now, and is more useful than ever!
* New option: Sky Detail. Set to high for more detailed clouds, but much less fps. Set to low for very crude clouds, but heaps of fps.