I was just listening to Glenn Beck and he reported that he heard a law enforcement officer on scene state that with the white smoke and the smell after the explosion that it smelled like a gun powder bomb. So, now we know the next stage in the gun confiscation and restrictions plan which is to curtail the ability to purchase black powder, gun powder and reloading supplies.
I did a quick online search and found this:
Bomb Experts Offer Analysis Based on Details from Boston Marathon Explosions
Likely a high-powered black powder pipe bomb; potential domestic terrorism, experts tell U.S. News
The explosions at the Boston Marathon on Monday were likely caused by high-power black powder explosives, bomb experts tell U.S. News, and at least one of them was likely shaped in a pipe bomb.
The white smoke that emanated from the blasts indicate this was likely a smokeless or black powder, he says, not a military-type explosive such as C-4 or plastic explosives, which give off black smoke. Two explosions in quick succession also indicate this was likely a terrorist attack. SOURCE