IPython Notebook Tab-Complete -- Show Docstring

I just upgraded to IPython 2.0.0 and the behavior of tab-complete seems to have changed. (Using pyreadline 2.0, which according to this question might matter). Formerly, if I hit TAB after `function_name(`, IPython would show the docstring for that function. Now, I just see a dropdown list of what I guess is everything in the namespace, including: - Error types - names of other notebooks in the directory - IPython magic functions - Other functions I've defined - etc. The old behavior was super helpful -- how can I restore it (short of reverting to an earlier IPython version)?