Is Trust public in Ripple? If I trust someone, does everybody see exactly how much I trust them?

At some point, a public directory of Ripple addresses might emerge, and people will know exactly how much their friends trust them, compared to how much they trust their other friends which might be awkward.
Trust must be public because other people can use it. I agree, this can be awkward.

I don't see community/private credit as a major use case for Ripple in the short term because of issues just like this. But I hope that in the future, and maybe even with changes in social conventions, this may change the way people think about money.

Look at how transparent people are now on Facebook. They publicly friend people and defriend them. So it could happen.