We've known for a little while that players have been able to light Nether portals with lava or fire blocks despite portal creation being disabled, which has led to at least one incident of a portal being created within another players area without their knowledge.
This bug has now been fixed and although portals will still light using these methods they will no longer work or create portals in the other world and hence can no longer be used to grief. Existing portals will also no longer work.
So once again the only way to get to The Nether is via the WorldWarp at spawn.
