I've had the same thoughts about this. However, to make database commits you have to know the big picture, and your data access objects don't.

One approach would be to make a set of "action" objects that are allowed to manage transactions and call the data objects, but have no web-specific code in them. This would be similar to what the Java folks call a "session facade". In Java this is done because EJB performance sucks rocks, but in this case it would simply be an organizational tool.