When the MtGox intrusion was originally announced, Amir posted that it would likely result in a forced reduction in refunds of 30%.  However that was based on refunding users at a price of ~USD 5 per BTC (the figure being used when Bitcoinica was taken offline after the MtGox hack).  The increase in BTC price plus the return of some of the funds from the MtGox breach should close that gap in theory, but liquidation costs now need to be factored into the equation and liquidators typically charge upwards of $200 per hour. 

A liquidator can only give preferential treatment to unsecured creditors in limited circumstances, so if some unsecured creditors have received a 50% payment and those creditors aren't entitled to be treated as preferential, the liquidator will need to ensure that either other unsecured creditors also receive a 50% payment or claw back the 50% payments which have already been made so that other creditors are not disadvantaged by those payments.  We know that there is currently at least 20,000 BTC and USD 100,000 in the Mt Gox account but we don't really know the dollar value of 50% initial payments yet to be made.