Just a quick note that the 1.0-pre2 release was posted today.

Noteworthy changes in this release:
-interactive console now honoured in single-player (just in the stdin/stdout console where you launched the game)
-more console commands (change world hostile/peaceful, change user survival/creative, teleport player)
-completely new world generator to replace the old flat generator
-storage versioning was added (so future releases can either adapt storage data or fail-out with a more meaningful message)
-text rendering in the client has been improved (fixes the bottom of the "Q" from not showing up, for example)
-hostile mobs now don't spawn within 16 blocks of a player

A note on the roadmap:
-"sky light" was originally something I had been wanting to avoid, since the world is fully 3-dimensional, meaning it wasn't obvious where the "top" of the world was or if solid blocks exist thousands of blocks up
-however, this has resulted in the world being far too dark (in fact, I thought there was a world-gen bug since I couldn't find carrots but it turns out they were just too hard to see on the dirt in the dark)
-therefore, I have decided that some kind of sky light and time of day mechanics are required for initial release
-to this end, I have adjusted the roadmap so the next pre-release will include this feature and other pre-release plans have been bumped out (network stress, for example)

This means that 1.0-pre3 will be about the new sky light mechanic (this will likely be incredibly basic) and further balancing of the new world generator (as I suspect that the constants in it will need to shift to increase abundance of ores, etc).

Otherwise, the new world generator does make a big different in the feel of the game. Playing it is starting to feel more interesting and less just like testing software.

Give it a shot,
Jeff.