- If you haven't already, download the free iBooks app from the App Store.
- Locate the application in the Finder. (Select iBooks in iTunes and choose 'Show in Finder' from the File-menu. It will be named 'iBooks 1.5.ipa').
- Make a copy of the file.
- Change the file-extension of the copy from .ipa to .zip.
- Extract the resulting zip-file by double-clicking on it. You will get a folder named iBooks 1.5.
- In this folder open the Payload folder to find the app 'iBooks.'
- Right or control-click on the application to show the contextual menu and choose 'Show Package Content.'
- A folder will open with the font files in it. (The easiest way to locate them is to search the folder on .ttf.).
[crarko adds: Works as described. As always with fonts, be aware of copyright restrictions when making use of them.]

