No.
What caused this misconception was a study commissioned by Proctor and Gamble (Pampers!) in 1991. They wanted this study done because the US government was considering a ban on the use of disposables because of the harm they cause to environment. This study was found to be misleading by the Advertising Standards Authority in Great Britain and was prohibited from being mentioned in advertising.

This study was flawed in many ways. It did not take into consideration the transportation of the disposable diapers or the complete manufacturing process. It also didn't take into consideration the severity of the pollution produced. The water waste from the manufacturing of disposable diapers contains highly toxic and carcinogenic substances. Water waste from cloth contains only fecal matter and detergents, which are processed properly in sewage plants.

Disposables use 37% more water in their production than home laundered or service laundered cloth diapers. With the advent of high efficiency washing machines that have cut water consumption from an average of 30 gallons per load to 5-7 gallons, this percentage is even higher.

Disposables use more resources than cloth. See our page on the environment for a partial list of the resources necessary to diaper just one child in disposables. Many of the resources used for disposables are not renewable.

Disposables consume 70% more energy than cloth. This is figure may be higher now considering the improvements made in the efficiency of washers and dryers in the last 15 years.