As usual, a new Blender release comes with many additions, improvements and fixes in the Python API and bundled scripts. But that's not all, new features include Python ipo drivers and evaluation for any button that accepts numerical values in Blender.
The 2.42 BPython API has been expanded with support for groups, modifiers and constraints, among other features.
As always, many bugs have been fixed and the documentation was improved and updated for the new features.
For detailed information: mediawiki.blender.org/index.php/Release_Notes/Notes242/Python
Many valuable tools were updated or added for 2.42, for i/o, mesh processing, weight and vertex painting and more. Examples:
Self Shadow VCols (AO) in the Paint menu in Vertex Paint mode, for fake (but fast) ambient occlusion using vertex colors (see image at the left).
Poly Reducer, in the Mesh->Scripts menu (3D View in mesh edit mode), a good decimator that preserves weights, uv's and vertex colors.
Blender import and export support has been improved and expanded:
Some scripts were updated and made more robust and others have been added, as you can see in Blender's File->Import and File->Export menus.
Special mention: COLLADA 1.4 (with Physics) import / export. All main 3D modelling programs read and write this open format and more and more applications are getting support for it, too, so it's becoming the much needed de-facto standard. Notice: the COLLADA scripts require a full Python installation, the modules that come with Blender are not enough.
Learn more about adittions and updates here (includes pictures): mediawiki.blender.org/index.php/Release_Notes/Notes242/Scripts
PS: Python coders keep coming up with more and more good scripts, many useful, some even surprising! Only a few of them are included with Blender itself, so don't forget to check other places to know about what is going on: www.blendernation.com/category/python-scripts/ , blenderartists.org/forum/forumdisplay.php
Python can now be used to evaluate expressions when filling in numerical values. This is done by typing a hash symbol (#) followed by the expression to evaluate.
For example: #5+4-2 would return the value 7
This is a trivial example, but the evaluation process has access to all the same goodies as Python Ipo Drivers, so the possibilities are endless.
More informations about button evaluation (and pydrivers) here:
mediawiki.blender.org/index.php/Release_Notes/Notes242/PythonTools
This is a feature that was planned for Ipo Drivers from the start, but the 2.41 release came before we could implement it.
Python Ipo Drivers (or simply pydrivers) allow users to control ipo channels with expressions, instead of other object's properties, like with normal ipo drivers.
So they can do all an ipo driver can and much more. The only restriction is that the Python expression evaluates to a real number (integer, float), naturally.
They are accessible in the Ipo Curve Editor window when a channel is selected, via the "Transform Properties" (called "Channel Properties" in the View menu, shortcut: "n") panel. Simply press "Add Driver" and then the small green Python icon to get to the string field where you can enter an expression.
This page explains pydriver (and button evaluation) usage and features in detail:
mediawiki.blender.org/index.php/Release_Notes/Notes242/PythonTools