There's an SQL database that's been running since midnight storing all block changes, should be easy to repair griefing from now on.
EDIT:
looking over database, bloody hell you people play a lot.playername time
qazwsxal 00:02:20
Orcinus_JW 00:04:56
THE_TrashMan 00:42:35
Saratje 02:19:12
PD_Top_Gun 02:44:35
Actually learning SQL, the only TNT detonation that has so far occured was earlier today caused by Sara. It was located at (50,36,-306) and caused the detonation of 21 other TNT blocks, destroying 1404 blocks in total, consiting of 1123 cobblestone, 212 dirt and a smattering of others.