In a recent sales report it has been announced that Nintendo have sold 9.55 million GameCubes worldwide.

The full sales figures can be found below in the image and a detailed report can also be found in the pdf file below.

These numbers agree with Sony's, who stated that Nintendo are second worldwide but contradict with Microsoft's who seems to think that they are second.

The image with the sales figures can be found here.
The pdf file can be found by clicking here. You need Adobe Acrobat to view the file.