In order to be able to use PyRoot within the IPython notebook, you need to have the PyRoot extension compiled into ROOT. That is explained in a straightforward way on the ROOT website but it isn't quite as simple when you use Anaconda's version of Python. To get it to work, I found this reference that implies one needs to fix the library references with otool.
cd $ROOTSYS/lib
otool -L $ROOTSYS/lib/libPyROOT.so
sudo install_name_tool -change libpython2.7.dylib /Applications/Anaconda/anaconda/lib/libpython2.7.dylib libPyROOT.so
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import ROOT
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