There's a revised edition of the Bob Griesemer OWB book from Packt Publishing - Oracle Warehouse Builder 11gR2: Getting Started 2011. It's a good book for beginners and leads you through the basics of building an OWB project using OWB 11gR2 with a mixture of data sources including Oracle and Microsoft SQL Server. Its easy to follow and is essentially a tutorial for those new to the tool. Its always interesting reading different users views on what they use and what is important. The book includes updated information including the new user interface and code template mappings amongst others.
The book is here: https://www.packtpub.com/oracle-warehouse-builder-11g-r2/book