I know that eventhough iPhone is quite popular and was sold millions, there are only a handful books which will meet your "geek" expectations keeping the high quality. Technology enthusiasts generally don't approach such manuals because they can reach the needed information by searching, in forums, asking the other experts online etc.

iPhone: The Missing Manual: Covers the iPhone 3G covers iPhone 3G in such detail and with tricks, tips that you will never meet elsewhere.

This best selling iPhone book helps you accomplish specific tasks with complete step-by-step instructions for everything from scheduling to web browsing to watching videos. Another purpose of the manual is to speed up your usage of iPhone by increasing efficiency by teaching you the all hidden aspects of the cool gadget.

#1 Selling & Best Recommended iPhone 3G Illustrated Book at Amazon