Bukkit

1.6
Lazily create interfaces for soft dependencies since they may not yet be enabled.
Fix issues with villages.dat and idcounts.dat not being separate for instance worlds.
Fix World.getWorldFolder() throwing ClassCastException for instance worlds.
Do not cache chunks from instanced worlds in memory.
Do not keep spawn in memory for instanced worlds.
1.5
Add support for using WorldEdit's selection tool for portal creation.
Declare soft dependencies correctly in plugin.yml
Cleanup soft dependency code so it's much less likely to break plugin startup.
Added a lot of logging to soft dependency loading.
Fix issues with overlapping portals.
1.4
/icmd now just places a command block in your hands.
/icmd related permissions are now applied when users edit the command block by right clicking.
Custom packet handling to allow editing command blocks without OP.
1.3
Fixed a bug where instances where not removed from a party when they are deleted, causing an exception when subsequently they were deleted again.
Added /ispawner create command to turn an Entity into a spawner.
Improved /ispawner command to instantly update the spawner rather than having to wait for it to spawn a monster.
Improved TileEntity writing code to cause the client to update immediately.
Fixed a bug where the plugin detected Multiverse-Inventories as present when it is not.
1.2
Fix bug where homes and spawn setting were sometimes lost on a server restart.
Added /icmd command for creating and editing command blocks, with ability to restrict command usage with permissions.
Cleaned up code for reading & writing TileEntity NBT data.
1.1
Allow setting the spawn world to none, to avoid conflicts with other plugins. Note: if a player is in an instance which gets deleted, they will be teleported to the first world's spawn point if there is no spawn world set.
Added support for setting gamemode, based on a third party worldmanager's gamemode setting for the world. Multiverse is the only supported world manager.
Rewrote instance loading code, no longer requires destination world to be loaded.
Instances no longer always spawn monsters, this setting should be correctly cloned from the destination world.
Instances have their own chunk generator which only generates empty chunks.
Fixed bug with instance unloading happening whilst players are in the instance.
Fixed bug with instance unloading never happening in some cases.
Instance difficulty is now a setting on the portalpair, defaults to difficulty of the destination world at creation time.
Optimized onPlayerMove to only perform checks when the player has crossed a block boundary.