While the jury is still out, there is a lot of prelim. info available:
1) NASA Aviation Safety Reporting System (ASRS), flight crew reports of incidents suspected to be caused by personal electronic devices (PEDs), including cell phones.
http://asrs.arc.nasa.gov/report_sets/ped.pdf

2)US Congressional hearing on PEDs.
http://www.house.gov/transportation/...20-00memo.html

3) A lengthy NASA study of PED interference.
http://techreports.larc.nasa.gov/ltr...1-cr210866.pdf

What these all seem to boil down to is that in most cases, use of personal electronic devices, including cell phones, do not cause any discernable problems in the nav or comm systems of airliners. But, on the other hand, there have been cases where interference has occured.

My feeling on this is that even if only .01% ( one of every 10k) or less of cell phone calls cause interference of some sort, is it worth the possible problems that can result? Especially at the begining and end of a flight, being a few miles off course during cruise is not as big a problem as it would be during landing, for example.

From a personal standpoint, I would rather see the cell phone ban during flight continued just to avoid hearing the self important a**holes yelling into their phones for hours on end.