The Deutsche Bank and the NPD group have released the sales figures for the Xbox 360, PlayStation 3, and the Nintendo Wii. The install base for the Wii is currently at 13.4 million units, nearly two million units over the 11.6 million for the Xbox 360. The PlayStation 3 has sold just 5.7 million units in the US.
The first chart shows the progression of units sold in the United States since each console's release:

This chart shows the sales differences in terms of software, with the Xbox 360 leading the pack:
According to the chart, the Xbox 360 software sales are around 94 million units, the Wii is at 73 million, and the PS3 at just over 30 million.
Source
The first chart shows the progression of units sold in the United States since each console's release:

This chart shows the sales differences in terms of software, with the Xbox 360 leading the pack:

Source