CNN Worldwide is once again combining the on-air programming for CNN/U.S. and CNNI throughout the day today. Executives believe simulcasting Saturday’s coverage, which will be dominated by the situation in Japan, is more resourceful than both networks going it alone.

At 6amET, CNNI’s Andrew Stevens in Hong Kong and CNN/U.S.’s Randi Kaye in New York co-anchored coverage. At 9amET CNNI’s Becky Anderson took over from London as Kaye continued in New York. That will continue until 11amET, when Fredricka Whitfield it CNN Atlanta joins Anderson. At Noon, John Vause takes over for Anderson. Vause, an Australian who has worked for CNN in Asia, will anchor from Atlanta with Whitfield. Following all this?

The simulcast continues into the afternoon and evening hours.

Next Monday, CNN/U.S. will begin simulcasting two CNN International programs. At 4amET CNN will air “World Business Today,” anchored by Charles Hodson and Andrew Stevens from London and Hong Kong. At 5amET, CNN wills simulcast the newscast “World One” with Zain Verjee (left) and Monita Rajpal in London. Verjee is a familiar face on CNN/U.S. She joined the D.C. buro from CNNI in Atlanta in 2006. She spent three years in Washington, first as State Dept. correspondent and, later, news anchor on “The Situation Room.” Verjee returned to CNNI and moved to London in April, 2009. The two live hours replace a “Parker-Spitzer” reair at 4am and an “AC360″ repeat at 5am. “American Morning” begins at 6amET.

CNN International correspondent Richard Quest returned from rehab approximately two months after he entered in April.

Quest is the host of CNN Business Traveller on CNNI, and the monthly program continued in his absence. Andrew Stevens filled in in May and Adrian Finighan hosted in June and July (which debuts on Saturday).

We hear Quest returned to the London bureau in late June, and has spent the majority of his time working on the August edition of the program. He has contributed other travel reports for the network as well.

CNN Observations has found Quest’s first report since returning, from July 3.