Bokeh is an implementation of Grammar of Graphics for Python. Its primary output backend is HTML5 Canvas.
There are many excellent plotting packages for Python, but they generally do not optimize for the particular needs of statistical plotting (easy faceting, bulk application of aesthetic and visual parameters across categorical variables, pleasing default color palettes for categorical data, etc.). The goal of Bokeh is to provide a compelling Python equivalent of ggplot in R.
A related project is Pandas, whose DataFrame objects are directly used by Bokeh.
Bokeh has a function-oriented interface that closely resembles ggplot. These functions can be used interactively from the Python prompt, or from within a script (a la Matplotlib). Behind the scenes, these functions construct a scenegraph and data transformation pipeline that consists of nodes which can export their state into JSON.
The JSON representation of the graphic is then embedded in an HTML document which also contains the Bokeh JS runtime. This runtime is built on a port of Protovis to HTML5 Canvas, and consists of some higher-level canned plot layouts built on top of the Protovis framework.
For the initial prototype, Bokeh is implemented as a wrapper on top of the Chaco plotting system, and displays its output using Chaco. This will change as we implement the Javascript/HTML backend.
You can install the following with easy_install, "pip install", or they may be available for your Linux system via the system package management. If you are using a distribution like the Enthought Python Distribution or Python(X,Y), then you already have them installed.
Bokeh is a new project (March 2012), but is under active development by contributors at Continuum Analytics. Our goal is to get a 0.1 release that will consist of the basic data processing and backend rendering, and then solicit examples from users and help from other developers to start rounding out the features, defaults, and overall usability.