Here's the scoop from COGAT

From the Israeli PM’s office:

In order to prevent a humanitarian crisis in the Gaza Strip, Prime Minister Ehud Olmert has decided to adopt a security establishment proposal to establish a humanitarian corridor in the Strip to assist the population. This would entail opening geographic areas for certain periods of time during which the population would be able to equip itself and receive the assistance. The exact details will be determined by the Coordinator of Government Activities in the Territories [COGAT].

And from COGAT direct (our bold):

Following the decision of the Israeli political echelon, as of today (Wednesday, 7 January 2009) the IDF will refrain from fire throughout Gaza City for a period of three hours a day, in order to provide a "humanitarian corridor" for the people of the city. During this time, the residents of the city will be able to acquire basic necessities, and damaged infrastructures can be repaired. Today, Wednesday, the IDF will halt all fire in Gaza City from 13:00-16:00 (1:00-4:00 pm).

In addition, about 80 trucks carrying food, medicine and basic equipment are scheduled to pass into Gaza via the Kerem Shalom crossing. About half a million liters of fuel are scheduled to pass through the Nahal Oz terminal, as well as 60,000 liters of fuel to be transferred for the first time by truck via the Kerem Shalom crossing.