Things will probably get very interesting in the next few day, as AndRand states, many airlines have sent planes up for test flights, with no problems.
This, combined with the fact that many airlines are stating they will go bust if it continues, will make it a bit of a torrid time for the airline safety board.
Who makes the call?, surely if there is even just a slight chance that the ash cloud could cause problems then thats enough to warrant the flying ban?, or do "WE" just accept that this is one of the dangers in flying?.
Certainly not an easy call to make.