A very interesting paper on the subject:
http://www.endo.gr/cgi/reprint/NEJMsa0810119v1.pdf ,
and there's some background material about it at
Annals of Medicine: The Checklist : The New Yorker
The critical quote so far as I can see is from the results of the first paper:
The rate of death was 1.5% before the checklist was introduced and declined to 0.8% afterward (P = 0.003). Inpatient complications occurred in 11.0% of patients at baseline and in 7.0% after introduction of the checklist (P<0.001).
In other words, they roughly halved the death rate in operations by use of a checklist. Given that we've been using checklists of this nature in aviation since I believe the late 1940s, it's just astounding that it took so long for medicine to catch up.
G