That PSP figure is wrong - Game Spot combined PSP production shipments with shipments to retailers, which is redundant.
The 50m PSPs shipped to retailers that you cited is through January - PSP was at 49.7m through December 2008, and shipments in the past two quarters bring it to 53m or so. Sell in is what Sony calls sales to retailers, i.e. shipments.
You can see how big the differences in shipments vs production shipments can be by comparing production shipments http://www.scei.co.jp/corporate/data/bizdatapsp_e.html for the March 2007 year on there (25.4-17.0m) with the sales to retailers (shipments) reported here for the same year http://www.scei.co.jp/corporate/data/bizdatapsp_sale_e.html.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu
