TeXShop

There are two changes:

The folder ~/Library/TeXShop/Engines/Inactive/PreTeXt was revised and the three main PreTeXt engines were rewritten. Consequently, many more examples in mathbook can be typeset with TeXShop.
The Help menu contains a new 180 page manual for TeXShop. This help manual can be printed if you want a hard copy, and it can be converted to a stand alone pdf file by selecting "Save as PDF" in the print dialog.
The Help menu also contains a TeXShop Help Panel. This collection of web pages was the older way of documenting programs, but we stopped updating the panel around the release of Lion.