Sega's had smaller hits on Wii too, like Ghost Squad or Monkey Ball. At the least they've not had any huge flops like VF5 or Sega Rally Revo on HD...
I'd really like to know the state of their downloadables games sales though. They're no doubt banking on Virtual Console, and they've had a few notable hits on XBLA (Rez HD, VOOT). I wish we could get some hard (digital) numbers though...