[12w27a] Minecraft Pre-Release

Boats, when broken, now drop boats
Re-added debug graph on F3 menu
Signs are stackable now: Crafting them now gives 3 signs instead of 1, stack up to 16
Added /debug command to enable and disable profiling
Changed a few things around pistons - Most contraptions still work fine, but some require changes to repeater delays and similar. Overall, pistons should have fewer bugs, but will appear to update slightly slower.
Improved performance on MP and SP, including reduced CPU, RAM & bandwidth requirements
When opening SP worlds, users are now given their local IP address & port instead of hostname & port to avoid OS conflicts
Creative mode inventory now shows potion effects
Fixed some bugs
Fixed /kill not working
Fixed powering specific glitched pistons crashing the game
Fixed a visual bug causing pistons to be partially invisible or in the wrong location momentarily
Fixed being able to place portals in the nether in locations where they would end up in illegal locations in the overworld
Fixed the game crashing when publishing SP worlds with certain language settings
Fixed players on minecarts, boats or pigs and spider jockeys not being displayed in the correct location
Fixed a bug with dispensers
Fixed /say not accepting some strings form the console, often triggering the help dialogue
Fixed being able to transmute blocks to certain data values using an orientation-dependant tripwire bug
Fixed drinking potions in creative not consuming the potions, but still giving empty bottles
Fixed signs sometimes not saving the text when placing them