Gamasutra has an article on Big Fish Games’ CSO explaining that the “hardcore” and “casual” aren’t sufficient categories to divide the market up, and arguing that we need more categories with more kinds of game. Which is true, but I can’t help finding it a little ironic considering the source.
Meanwhile, I’ve been playing some of Chocolatier’s The Great Chocolate Chase, which is a time-management variation on their usual theme. It’s almost entirely a replay of Diner Dash, Cake Mania, Vogue Tales, etc., which is disappointing. It’s also not as well tuned as it could be: at least, I got relatively smoothly through quite a few levels and then have completely bombed out at level 40, which I can’t pass despite many replays: even if I manage to serve every customer without turning any of them away (quite a feat at this level), I’m not making my target for the day.
I’m very slightly curious about the (slender, minimal) threads of story built into the game, but that may not be enough to propel me past this plateau.
Emily Short's Interactive Storytelling 
There’s a little more detail at the post here.
I find the part about time spent playing most interesting:
some casual segments such as “Tycoons” (simple simulation and tycoon games) and “Clickers” (time management, marble popper and brick buster games) spent more hours gaming per week than the largest of the core gamer segments, Heavy Action.
I’ve always found the casual = not enough time to play mantra suspicious.