Alright, so maybe the president is (a dud), but according to this news story, the grenade near the president in Georgia, was.

From the story:

A hand grenade found close to George W Bush during his visit to the ex-Soviet republic of Georgia was armed and could have gone off, an FBI agent has said.
Bryan Paarmann also said the device had been hurled before falling into the crowd listening to the US leader's speech in the capital, Tbilisi.
It was found 30m (100 feet) from the stage in Freedom Square.

So, I'm not fan of GWB, but I'm even more opposed to our president being assassinated. Maybe we should be more careful, huh?