http://www.minecraftforum.net/…rly-teaser-info-released/
"Jeb tweeted that this week's Snapshot will likely come tomorrow, instead of the usual Thursday release time. In addition, he released the following information for key changes likely to be seen in the coming update:
Maximum build height has been increased to 256 (was 128)
Empty sections of the world are not loaded into memory
Block ids have been increased to 4096 (was 256) by adding a 4 bit data layer (similar to how meta data is stored)
Block ordering have been changed from x/z/y to y/z/x in order to improve compression
Packets for sending chunks have been updated (a full 128-high chunk is smaller than the old format, and a chunk with lots of empty space is much smaller)
Biomes are saved per x/z column, which means they can be altered by tools
In addition, he offered a glimpse into a new map format, as well as changes to the file format for save games"
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I cant wait till this trickles down into the main updates
Things interesting me are:
>Block ids - 4069 of them (Mods All you can add buffet)
>Maximum build height now 256 block high
>Bigger Chunks using less space