Is it possible to set indent settings in Xcode per project (or per file, even)?

The accepted answer is no longer correct.. as of Xcode 5.1.. which forces you now to Edit "per file" indentation settings via..

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You can set indentation per file, group, project, or for all new projects, and for all but per file indentation, new source code files will inherit the indentation settings of the closest parent.

To set indentation per file, select the file in the Project Navigator, and set indentation in the File Inspector ▶ Text Settings.

To set indentation per group, select the group in the Project Navigator, and set indentation in the File Inspector ▶ Text Settings.

To set indentation per project, select the project in the Project Navigator, and set indentation in the File Inspector ▶ Text Settings.

To set default indentation for new projects, select Xcode ▶ Preferences... ▶ Text Editing ▶ Indentation:

This seems to have changed with Xcode 4 ... if you click on a file, group or project, amongst the items in the Utilities bar (at the right-hand side, by default) is 'Text Settings'.