The jury is still out as to whether surgical checklists used in a first world environment makes substantial savings of life or reduces complications significantly. The benefit seen in Gawande's trial  may have all come from the third world hospitals that were also included but as far as we know, the hospitals were not made public as to which were which. That condition may have been part of the reason why they chose to participate in the first place. They included the hospitals from following locations:
eight hospitals in eight cities (Toronto, Canada; New Delhi, India;
Amman, Jordan; Auckland, New Zealand; Manila, Philippines; Ifakara,
Tanzania; London, England; and Seattle, WA)
A large trial from Ontario, Canada was published in March 2014, and showed different results. 
During 3-month periods before and after adoption of a surgical safety
checklist, a total of 101 hospitals performed 109,341 and 106,370
procedures, respectively. The adjusted risk of death during a hospital
stay or within 30 days after surgery was 0.71% (95% confidence
interval [CI], 0.66 to 0.76) before implementation of a surgical
checklist and 0.65% (95% CI, 0.60 to 0.70) afterward (odds ratio,
0.91; 95% CI, 0.80 to 1.03; P=0.13). The adjusted risk of surgical complications was 3.86% (95% CI, 3.76 to 3.96) before implementation
and 3.82% (95% CI, 3.71 to 3.92) afterward (odds ratio, 0.97; 95% CI,
0.90 to 1.03; P=0.29).
and they concluded the changes were not significant.
Implementation of surgical safety checklists in Ontario, Canada, was
not associated with significant reductions in operative mortality or
Atul Gawande blogged on the results of that trial  complaining that the participants lacked adequate training in the use of the checklists, and that there was no independent check on their compliance. The authors deny that these were important aspects.
Interestingly, lacking any well controlled double blinded trials in checklists, Gawande has turned to simulation testing in a crisis situation, and here the results favoured checklists. 
A total of 17 operating-room teams participated in 106 simulated
surgical-crisis scenarios. Failure to adhere to lifesaving processes
of care was less common during simulations when checklists were
available (6% of steps missed when checklists were available vs. 23%
when they were unavailable, P<0.001). The results were similar in a
multivariate model that accounted for clustering within teams, with
adjustment for institution, scenario, and learning and fatigue effects
(adjusted relative risk, 0.28; 95% confidence interval, 0.18 to 0.42;
P<0.001). Every team performed better when the crisis checklists were
available than when they were not. A total of 97% of the participants
reported that if one of these crises occurred while they were
undergoing an operation, they would want the checklist used.
 Haynes AB, Weiser TG, Berry WR, Lipsitz SR, Breizat AH, Dellinger EP, Herbosa T, Joseph S, Kibatala PL, Lapitan MC, Merry AF, Moorthy K, Reznick RK, Taylor B, Gawande AA. A surgical safety checklist to reduce morbidity and mortality in a global population. N. Engl. J. Med. 2009 Jan;360(5):491-9. doi: 10.1056/NEJMsa0810119. PubMed PMID: 19144931.
 Urbach DR, Govindarajan A, Saskin R, Wilton AS, Baxter NN. Introduction of surgical safety checklists in Ontario, Canada. N. Engl. J. Med. 2014 Mar;370(11):1029-38. doi: 10.1056/NEJMsa1308261. PubMed PMID: 24620866+.
 Arriaga AF, Bader AM, Wong JM, Lipsitz SR, Berry WR, Ziewacz JE, Hepner DL, Boorman DJ, Pozner CN, Smink DS, Gawande AA. Simulation-based trial of surgical-crisis checklists. N. Engl. J. Med. 2013 Jan;368(3):246-53. doi: 10.1056/NEJMsa1204720. PubMed PMID: 23323901.