Actually, Bokeh plots are not (yet) integrated with the widget infrastructure at all, and work in IPython 1.x. There is a fully embeddable javascript library (BokehJS) which handles all the interactivity entirely in the browser. Data can be directly and fully embedded in the DOM.
If you want to view larger data, access the downsampling capabilities of the Bokeh plot server, coordinate views between multiple instances of the notebook, or do streaming and animated plots, then you will need to run the bokeh server.
If you want to view larger data, access the downsampling capabilities of the Bokeh plot server, coordinate views between multiple instances of the notebook, or do streaming and animated plots, then you will need to run the bokeh server.