I have always found the notion of "public intellectual" interesting, but slippery--particularly given that there can be quite a plurality of publics. (The Church, as a public, might have a different set of public intellectuals than, say, the "public" as defined by the NYT. I've often thought that if a particular congregation represents a certain "public," then there should be a sense in which the pastor is its public intellectual. I think this has traditionally been the case in black churches, and was historically in Protestant churches.)
In any case, Prospect magazine, in conjunction with Foreign Policy, recently proposed The World's Top 100 Public Intellectuals. An interesting list to browse (keep in mind that one of the criteria was that the figures must still be alive). Several philosophers make the list (e.g., Dennett, Walzer, Rorty), a couple of theologians (Benedect XVI and Hans Kung), couple of cultural theorists (Negri, Zizek), and my favorite journalist, Christopher Hitchens.
One interesting lens through which to think about the list: I don't know if there is a single Protestant on the list. What about Rowan Williams? Or Cornel West?