Well, the conventional wisdom on the left is that one's social location (identity) shapes (not determines) one's beliefs and political views. It's watered down standpoint epistemology, most notably pursued by black radicals themselves, in the sixties, but also (and not surprisingly given the assumptions they built on from the work of the bearded wonder, among others, such as E.B. DuBois (who was very influenced by Hegel, coining the phrase "double consciousness" in the essay, 'Of Our Spiritual Strivings'.)
Thus, it's not exactly that anyone is expecting blacks to do anything that many black radicals and progressives have, themselves, asserted, argued, etc. The most widely read example of the first clarion call espousing such an identity politics, which clearly suggests people of color should be smarter than whites is The Combahee Collective's statement where they claim that it is by virtue of their extreme marginalization from society that black lesbians would be the ones to make that first "revolutionary leap" paving the way for -- snap! -- radical social change of the sort so many believed was happening at the time.
It continues, today, in the form of blog wars among feminists and liberals (firedog lake, kos, and some others being prominent offenders) where black women and women of color more generally have pointed out, repeatedly, that none of these supposed "liberal" and "progressive" movements of mostly white men will get anywhere without women of color, etc.
And yet, it's not exactly like these bloggers are hotbeds of radical class and racial analysis either. And while they often speak to the issue of dems being no different than republicans, when push comes to shove.... they typically can't fathom what to do if not vote for a democrat.
Bitch | Lab http://blog.pulpculture.org (NSFW)