Considering Notch just got married recently. Like a week or so ago, I can see why it would be delayed.
Minecraft is going through a huge update, from a Sandbox game, to a hopefully interactive Game.
A lot of new content is being put into it, about as much if not more than you would expect to see from an expansion in other games. Those games take months of creating, debugging and the like.
~~~~~~
As for those who wonder what the appeal to the game is: It is a lot like Lego’s, if you want to build something, you can build it. If you want to level a mountain, you can. You can play the game however you want to play it. And if you get bored, you find a Mod, download it, and play it.
In the end, the questions are, are you goal oriented? Do you like to build things, fight things, explore? Are you creative, Will you make yourself a castle; an underwater laboratory; a city; a world?
Some of the things I’ve seen people build:
Battleship
Mines of Moria
Roman Coliseum
USS Enterprise
Pantheon
And a lot more.
Best part for me, being able to play with friends and work on projects together.
~~~~~~
As for the problem with the game lagging it is a mix of all the information being kept track of, AND the graphics.
The graphics card has to have the information so it knows what to display when. So it’s more of how much RAM the video card has, more than how powerful it is. (Not a lot of calculations going on, as its all blocks, not a ton of polygons which is what powerful graphics cards are meant for.)
Chunks are 16 blocks wide, 16 blocks long, and 128 blocks deep, which is 32,768 blocks total. When wandering the world the nearest 81 chunks are loaded, arranged in a 9 by 9 grid around the player.
These chunks may have activity (mobs spawning, trees growing, water flowing, dropped items disappearing etc.), while the other world chunks are inactive, stored on your hard drive.
If a player goes to an area that is beyond the already generated chunks, new chunks are generated and stored to the drive.