My cherry tomatoes have quite a few yellow shoulders -- we've had a lot of rain last week, so there's a lot of cracking too.
Some are exposed to sun, they don't seem "tough" so I don't know if it's sun scald, high temps, too much water, or a soil imbalance. I read the green shoulders thread, just didn't know if this is the same deal.
I do have some green shoulders on the plum tomatoes, and the Mountain Magics (salad tomato) are just fine.