I mentioned this on the new boarding process thread - the flight to Glasgow last week they were doing the pre-boarding for people checking in hand baggage. I personally think this is a good proactive exercise, and on the two flights I've been on when they have done this we departed on time. However, I cannot remember the last time we were delayed due to hand baggage issues.
Also, there were 17 people (of the 50 plus who took the offer) who had 3 items of hand baggage. You could see them checking in one item and boarding with two - this does nothing to solve the problem.
If policed correctly it is a good step forward, if not it is just another benefit which will be exploited by the p^*$ takers.