As far as I know, there is no book covering RapidMiner. Beside: RapidMiner is a Tool for DataMining, so reading books about Data Mining will help you to get an idea what you can do in general. Then it might be easier to find the right steps in RapidMiner or to ask precise questions to the community.
After my first two weeks of analysis with RapidMiner, I spend the time to read the complete OperatorReference. I forgot a lot (of course), but at least I got a slight idea what is possible and where I can find it ("hm...I have seen something like this before...").
The question for more real-world examples is often asked, but it is the community which should create them and add them to RapidMiner Wiki...
Just a few thoughts...
PS: There are some more tutorials for RapidMiner Plugins, e.g. Web/Text and Time Series / Stock Analysis (lost the link)
After my first two weeks of analysis with RapidMiner, I spend the time to read the complete OperatorReference.
Wow. That's pretty cool and actually you are the only person I know of who read the whole reference then. But it seems to be worth the effort since you are often able to come with solutions even in cases where most other people (including myself) would have a hard time finding the process. So I should recommend reading the reference more often - although it's about 400 pages
How to load processes in XML from the forum into RapidMiner: Read this!