This is pretty big news - all currencies are built on confidence and Bitcoin has been making good steps to build it but I guess this attack has exposed a real issue for Bitcoin; without a lender of last resort or Central Bank, if the technology stumbles what do Bitcoin holders have?
A “massive and concerted attack” has been launched by a bot system on numerous bitcoin exchanges, Andreas Antonopoulos has revealed. This has lead to popular exchange Bitstamp putting a temporary halt on all bitcoin withdrawals, and BTC-e announcing possible delays on transaction crediting.
http://www.coindesk.com/massive-concerted-attack-launched-bitcoin-exchanges/