I think the cabin crew play a part in how attentive the passengers are to safety announcements.
On a recent 738 flight, Sydney - Brisbane, the two (beautiful) female flight attendants demonstrated the safety equipment, as the male crewmember conducted the briefing "In the event that this flight turns into a cruise!, your life jackets are located under the seats" etc.
Believe me, there was no one playing with their blackberry's.