This video recounts the anecdote and speaks for itself:
Some object to the fact that Uhura was portrayed in a tiny mini-skirt and thus cannot be considered a figure of empowerment, contrary to what Nichelle Nichols claims here. But remember the time, there were no black women portrayed in positions of equality and authority then ... there were few women portrayed in such positions period!
Remember that civil and human rights dimension the next time you see Star Trek and if you should see the new film (which I enjoyed) ask yourself, is the presentation of Uhura faithful to that original spirit of empowerment?
One final thought: The first interacial kiss on American Television was between the characters Uhura and Jim Kirk ... "boldly going where no one has gone before" indeed.