Hi Neeraj,
Yes, it is a huge challenge to keep the book up-to-date. The book was originally scheduled to come out in 2006. But I wanted to keep it updated with the latest Seam, and kept developing it in the Safari Rough Cut program for almost 9 months.
Fortunately, as Mark said, Seam has reached a relative stable release for 1.2.0. New features are still being added (e.g., we will have web services, Groovy, Quartz support in 1.3.0). However, the core set of Seam features and the Seam "way of programming" are pretty stable now. It is easy to understand those new features once you understand how Seam works overall.
The book intend to cover the ideas behind Seam with a lot of examples. I intend to maintain those examples for future Seam releases. Once you read the book, it will be easy to get to the Seam documentation for the latest features not yet covered in the book.
cheers
Michael