Bukkit

v0.5
+ New config options, whitelist and whitelist-block-ids.
+ If you wish to apply gravity to only a selected block type or list of blocks set whitelist to true and list the whitelist-block-ids.

v0.4
+ New config options, blacklist and blacklist-block-ids.
+ If you wish to prevent gravity being applied to a block type or list of blocks set blacklist to true and list the blacklist-block-ids.

v0.3
+ Added config.
+ Config option to allow items to drop if a block falls to an invalid location. For example onto a touch.
+ Added a scheduleSyncDelayedTask for performance and timing increase. This means you have more time to place a block beneath a block just placed before gravity is applied.

v0.2
+ Added permission node "gravity.apply"

v0.1
+ initial release.