Stonyfield Farm's YoTube. Particularly interesting in this light is what Google first tries to give you upon searching for "YoTube Stonyfield," though it will actually search for "YoTube" if you insist, at which point Stonyfield's site is the top result. Bonus: using autocomplete, type "YoTube" then, after a space, some other letter, and see whose fans can't spell.
I think Google's automated compensatory measures decrease the likelihood of confusion, by making sure you have to take affirmative steps to reach Stonyfield. I'm sure, however, that it would be easy to find a good trademark lawyer to say the opposite.
This also makes me think about how, for big brands, it's hopeless to try to see in any comprehensive way what's going on with your brand. What, are you going to set a Google Alert for YouTube? (Would YoTube show up on such an alert, anyway?)