At this moment MutliSig is not implemented as it is not practical and really only good for buyer/seller/escrow type marketplaces. If a trader feels anxious about holding funds on the exchange the most secure option would be to hold them in a privately owned wallet on their computer and only deposit the minimum required for trading. One of the security features that is being implemented is call TimeVault. When a trader stores funds in a time vault the funds are sent to a secure cold storage wallet and the user received a Txid so they can monitor this cold wallet on the block chain themselves. All withdrawals from the TimeVault are delayed for ~ 7 days so if a hacked gained access to your account you would have 7 days to before they could steal your funds where you could freeze your account. Similarly funds in cold storage cannot be accessed if we get hacked.

Security is a priority and we have the following security measures among many others:

Database:
    Atomic Request based Transactions
    ACID complient   
Wallets:
   Store the majority of customer funds in a cold storage wallet
   Double check withdrawal submissitions for overdrawing
Authenication:
   Passwords are stored as salted hashes
   Secure session based authentication
Input:
   Regex to sanitize input strings
   Limit post and get requests to minimize Denial of Service attacks and prevent cracking account passwords and other malacious activity.
   Protect against Cross-site request forgery using csfr tokens
Operating Environment:
   Hosted on Gentoo Hardened OS
   SELinux
   GRsecurity