I'm currently working on 1.6, which will be mostly a bug fix update. I will be going through bug lists (including the great one on the Minecraft wiki) and fixing as many as I can. There's no set date for the update yet as I don't know how long it'll take to go through the list.
The only new feature that will appear is the mapping.
When you craft a map, you will be able to somehow select how “zoomed in” you want the map to be. It will be centred on the location where you craft it, and it will fill in as you explore the land. If you go outside the edges of the map, it will stop updating, so each map is of a specific area. (like real maps!)
Here's a screenshot of a fully zoomed in map (good for town maps, for example):
And here's a screenshot of a fully zoomed out map:
If you drop a map and someone else picks it up, they will be able to see your progress. You will also be able to (somehow) CLONE maps so that two separate map items link to the same map data. That means you can see what other players carrying the same map explores, and both you and them will show up as blinking dots or similar on the maps.
Currently, the map will only update if you're holding it in your hands, but the map will kind of hide away when you’re looking straight forward. To see the map properly, you have to look down, thisly:
Any changes you make to the terrain will show up on the maps, but only once someone carrying the map gets near that area. In other words, you won't magically get to see changes far away on the map.
At the moment the map doesn't work at all in multiplayer, but that's my next task. The code I write to support that will also be possible to reuse in the future for things like books and notes written by players, and possibly even custom paintings/hand drawn signs.
There's a hard limit of 65536 unique maps per world, though, and I don't think I can get around that without breaking the code very bad. I'm trying to figure out if the limit is high enough or if I should spend the time rewriting the code..