As for mistakes:
Nintendo: Treating developers poorly until they walked away. Even the carts on the N64 did that, as developers insisted that they were not enough space, with not enough profit margin.
Sony: Turning the Playstations into kitchen sink devices, and forgetting that they were gaming systems more than anything else. The PSP may be selling on its multimedia, but that got more focus than the games. And the PS3 could have gotten away with its design (actually pretty close to the 360, but with the Cell, blu-ray, and mandatory HDD), but those parts were integrated hastily together, causing the system's infamous manufacturing cost.
Microsoft: Pumping money into everything but proper research into worldwide marketing.
A flashy-first game is awesome when it comes out. A great-first game is awesome forever.
Plus, just for the hell of it: Kelly Brook at the 2008 BAFTAs
