Quoting xyz:
[spoiler]Engine changes
99% lag-free; optimized server can handle 50-100-... players; no problems with laggy mods even on slow hardware
Much faster on client (VBO, can eat memory), increased view and send range (PilzAdam)
Directional fog + horizon colors based on sun & moon positions (MirceaKitsune #799 #772)
Adjustable dynamic weather and liquids (it's possible to define number of liquid levels in node)
Weather defined water or ice on map generation. (freezed oceans if low temperature) and dirt_with_snow instead of dirt_with_grass when too cold.
Weather defined tree and flowers growing
Cave trees in huge caves (indev mapgen)
Optimized falling (much less mid-air stuck, limited max falling speed, more air control at high-speed falling)
Fixed and optimized headless client (you can run 30-50 bots on one PC)
Hell (very hot at -30500), everything melting and burning
Slippery (Zeg9 #817)
Improved (re)spawn (don't spawn in stone) (sweetbomber #744)
Diagonal Rail (khonkhortisan #528)
Increase the amount of particles that breaking a node generates (ShadowNinja #943)
Player list, viewable by holding TAB key (sfan5 #958)
Improved math mapgen: more (10+)generators from
http://mandelbulber.com/, all params are adjustable
(minetest merge) sqlite rollback
And some small bugfixes and improvements.
API changes
New node groups: freeze, melt, hot, cold (define temperatures); learn how to use them here
New node group: slippery
minetest.register_abm({…, action(…, neighbor)}) — the action function has a new parameter called neighbor which will contain a node that was matched as a neighbor
minetest.register_abm({…, neighbors_range = 4}) — maximum radius to search for a neighbor in (for example, melting snow in 4×4 area around torch)
minetest.get_surface (sapier #640)
Game changes
dirt, sand and gravel will fall off the edges (try to build something ;)
Furnaces burn items even when they are unloaded (Novatux #200)
Moonflower (MirceaKitsune #175)[/spoiler]