The FDIC is adopting a Final Rule to implement its Temporary Liquidity Guarantee Program. The Temporary Liquidity Guarantee Program, designed to avoid or mitigate adverse effects on economic conditions or financial stability, has two primary components: the Debt Guarantee Program, by which the FDIC will guarantee the payment of certain newly-issued senior unsecured debt, and the Transaction Account Guarantee Program, by which the FDIC will guarantee certain noninterest-bearing transaction accounts.

The link above will take you to the FDIC decision. It is 102 pages long and deals with a plethora of matters, but the discussion on IOLTA accounts begins on page 44 and the decision creating the exception for IOLTA accounts is on page 46.