Bukkit

Treetop code got a redesign. Players will now cut trees as normal (same as Vanilla), and if a player leaves a treetop hanging for five minutes, it will be automatically cleaned up and replaced with a new sapling. Trees which are entirely cut down will stay cut down entirely (no automatic sapling).

Relevant config options with defaults:

• RemoveFloatingTreetops: true
• RegrowGriefedTrees: true