I made another chart from 2011-03-18 to 2011-06-18 using a log scale to try and get an idea where this might go if it happens to be a bursting bubble of some symmetry. With bitcoin over $15 it seems difficult to believe that it may go below $1, but the only other time bitcoin ever went above $1 was in February.
Could this whole spike to $30 really be just a bubble? Bitcoin is open source software of a digital currency backed by nothing of physical value. It is a new technology with a number of unknowns about wallet security, government reactions, price stability, merchant usage, and Bitcoin's ability to compete with future Bitcoin-like currencies which may be backed by things of physical value. As far as I know, there hasn't been enough positive change in these unknowns over the past couple months to justify the 30-fold run-up in Bitcoin price so it isn't too much of a stretch to consider this recent spike to be a media driven bubble of people who don't care much about Bitcoin as a revolutionary new currency and instead primarily view Bitcoin as a way to get rich, which is the driver of bubbles.