Users of the Safari Books Online service can sync their iPhone with the "My Downloads" library from their Safari account. Once downloaded onto your iPhone you tap the title of the book to open it. Books can be downloaded to your iPhone whenever an internet connection is present. They will be stored in and available within the Bookbag App.
More information about Safari Books Online can be found here where according to the site:
"Today Safari Books Online offers a depth and breadth of technical content that no other electronic reference resource comes close to matching. Safari Books Online has become the trusted search for technology information. Without question, Safari is fast changing the way that corporate, academic, and training organizations access information."