Is there a way to perform updates on a PIVOTed table in SQL Server 2008 where the changes propagate back to the source table, assuming there is no aggregation?
PIVOTs always require an aggregate function in the pivot clause.
PIVOT
Thus there is always aggregation.
So, no, it cannot be updatable.
You CAN put an INSTEAD OF TRIGGER on a view based on the statement and thus you can make any view updatable.
INSTEAD OF TRIGGER
Example here