Bukkit/Bukkit — pull request #616 by nitnelave (2012-05-28 14:17:48+00:00)
Title: Added BlockDetonateEvent

Fires when a TNT block is detonated (primed)
It is cancellable, and if cancelled, the TNTPrimedEntity isn't spawned, but the TNT block disappears.
It has a DetonateReason, which can be FIRE (for fire spread), FLINT_AND_STEEL (for direct player ignition), REDSTONE, EXPLOSION (if a nearby creeper or tnt exploded), CUSTOM or DEFAULT.

Test plugin : http://dl.dropbox.com/u/31201298/detonate.jar