Look, as required by federal law, corporations have to post what they have shipped in their financial reports (so that their investors know how well the company's products are selling).
Nintendo, Sony, Microsoft and most third parties see their financial years end in March. The data then is collected, and released publicly in April to May. Officially, the data through March is the most recent. To please investors companies will try to make themselves look as good as possible without truly lying (i.e. Sony did make 5.5 million PS3s for their warehouses. But only 3.8 mllion made it to retailers)
Leo there is absolutely no way Sony has sold 5.5 million PS3s. Whether or not you like VGcharts, Sony just announced they hit 1 million in Europe like two days ago http://www.gamesindustry.biz/content_page.php?aid=25649. They will probably be at 1.4 million (according to NPD data) through May in the USA and Canada http://www.gamasutra.com/php-bin/news_index.php?story=13996 . In Japan, Sony has not even hit 1 million yet. By Media-Create, Sony jus passed 900,000 in Japan.
So in terms of sold to customers, as close as you can get with official agencies, Sony may be at 3.30 million. Vgcharts is more current, and therefore has a higher number for Sony.
In contrast, Nintendo is at 2.5 million in the USA (2.9 million or so once May NPD comes out), about the same in Japan (2.6 million according), and 2.1 million in Europe. Then you throw in Canada, and you arrive at the worldwide Wii total.