Here follows the massed wisdom of our Users: if you are using any i-device…You need iTunes and iBooks (a free reader app in the app store). Open iTunes and click on the Books folder in the left sidebar. Drag the iPub file into this window. Make sure you have the iBooks reader installed on your iPhone and then sync your device.
Step 1. On your computer: Download the epub file from Closed Circle to your computer INTO the folder you use for epub. Step 2. Have iTunes and iBooks [free apps in the app store] installed. Step 3. Open iTunes and click on the Books folder/section in the left sidebar. Step 4. Drag the ePub file onto the Books screen/page of iTunes 9.2.
Step 5: On your device: Be sure you have the iBooks Reader installed on your iPhone [an app]. Step 6: Sync your iPhone/iPod Touch/iPad.
This should do it.