Here is the source:
http://www.coindesk.com/massive-concerted-attack-launched-bitcoin-exchanges/Bitcoin developer Jeff Garzik said the core bitcoin block chain consensus mechanism and payment system are continuing to work as before, and are not directly impacted by transaction malleability.
He added: Web wallets and other services that build services on top of bitcoin are reporting problems similar to MtGox, and are taking safety measures to ensure no fund loss, during this network disruption.
Yesterdays statement must be revised: we will likely issue an update fixing two edge cases exposed by this attack.
I hadn't seen that update. My intent wasn't to be controversial but to rather point out in plain english the types of issues that normal users running the reference client are likely to experience. I updated the title.
Well although the problem was known before, nobody exploited it on a large scale until now. And why now?