So very surprised about something we knew about in October of last year [http://www.escapistmagazine.com/forums/read/9.73702]. You even pretty much used the same link.
Doing a search over the net, Sonic Unleashed sold about 1.86 million copies across all platforms. To put that in perspective, a game like Final Fantasy XII managed 5.09 million on the PS2/PS3.
Yeah, Sonic Team's going to keep turning that money crank. You can shake your tiny fist at that and call it tripe, but apparently we're just not their key demo anymore.
If it's any consolation, Sonic Rush - a game that heralded back to 80s Sonic - sold about 2.47 million for a single platform. Sega should make more games like that, or so you'd think.