Just saw this segment on an Australian tv show. It is abit hyped up but it is kind of a worry. What if these DDOS attacks did put an end to mtgox? Would we lose everything like people with cryptoexchange did?
http://www.abc.net.au/7.30/content/2013/s3732468.htm
What people don't understand is that putting all your bitcoin into an off disk location is a huge risk and anyone that has any USD or cryptocurrency on those sites are putting it there at their own risk. There are no back ups of something once it goes down permanently.
I hold all my coins in my wallet and keep a backup of everything on a flash drive. That includes the roaming folder minus the blocks folder where all the block data is stored.
To keep it simple, only put something on an exchange site if you plan on buying or selling it immediately and transfer it immediately to a safe location. (Wallet for coins, paypal for money)