These Lion pages describe version 3 of TeXShop, which requires Lion and takes advantage of new features in the operating system. For a long time to come, TeXShop version 2 and TeXShop version 3 will be developed in parallel. TeXShop's "Check for Updates..." item will never update TeXShop version 2 to TeXShop version 3; instead it will only update within the version 2 family, or within the version 3 family.
Major features of version 3 are described in the Lion pages linked to the left and below.
MacTeX and TeXShop on Lion
MacTeX-2011 was released in July 2011, and has been extensively tested on Lion. Indeed, MacTeX-2011 was released on the same day as the Lion release.
All releases of TeXShop from version 2.39 on work on Lion, but version 3 is highly recommended.
The ~/Library Folder in LionThere is one small change in Lion which affects TeX. Each user's home directory contains a folder named ~/Library where configuration information for that user is stored. On Lion, this folder is hidden. But it is easy to open the folder. Select the Finder's "Go" menu, which has commands to open various important folders. When the "Option" key is pressed, "Library" is added to this list, and the new item takes you to your personal Library folder.
Recall that the ~/Library folder contains configuration files for TeXShop and TeXworks, and may contain a texmf folder for a user's personal style and font additions to TeX.