The latest quinquennial report on the status of the death penalty is now available on the website of the UN Office of Drugs and Crime. You will find it by a search using the UN document number E/2010/10 (you can also google the document number). This is the eighth such report, the first having appeared in 1975. I was the consultant to the UN in the preparation of the report.
The report shows a continuing progress in abolition, with a total of 149 States that are abolitionist de jure or de facto, and 47 that are retentionist. There is a graph showing the evolution of the situation since 1975, when a large majority of States still retained capital punishment. The report highlights the significance of the de facto abolitionist category, which consists of States that have not used the death penalty for ten years. Its usefulness has been debated, because of concerns that States return to capital punishment despite a lengthy period of disuse. But the report shows that such a return is very rare. As a general rule, where a State has been ten years without an execution, it is highly unlikely that it will ever again use the death penalty.
The report also examines the pattern of executions in States where the dath penalty is retained. In most such States, there has been a marked decline in the rate of execution.