"@MtGox Maintenance Over however we are now under a DDoS attack." [1]
Mt Gox has taken a credibility knock, which has a ripple effect on the BTC pricing right now.
Overall it probably a temporary setback, but does bring to light irrational exuberance voices ignoring others that were calling for a more decentralized ingress/egress between USD and BTC. IOW bitcoin needs more exchanges to drive competition, and perhaps even meta-exchanges too.
I don't think it's at all unreasonable to think that each of those sites would have naturally seen their greatest traffic surge with the events of yesterday. For example, over 20% of all subscribers were present on /r/bitcoin (for comparison, (eg) /r/android is currently at about 0.5%, /r/bitcoin is around 10% now).
I'll see if I can dig up sources.