I see that the Pakistani Taliban has claimed responsibility, but so far there is no hard evidence linking them to the attempted terrorist attack. I won't be surprised if it turns out that this was just the work of some lone wacko.
Right now I'd take pretty much any information about this incident with a grain of salt, until all the facts are in. Remember how the underwear bomber was described as a non-serious threat, just a laughable attempt at terrorism? Then we later learned that his bomb was actually a sophisticated device that could have brought down the plane. I've already seen several references to this bomb being crude or amateurish -- as if that somehow negates much of the threat. Unfortunately, explosive devices don't need much sophistication to be effective. They just need to go off with enough force in the right place at the right time. Fortunately this one didn't detonate.
This incident points out yet again the value of alert citizens who react quickly, in this case a t-shirt vendor who notified police about the suspicious vehicle. If that guy had acted like many people and just gone about his business, refusing to get involved, we might now be talking about the aftermath of a nasty explosion.