This is a very important step for Packt because it means that they are continuing to support in a great way Open Source in terms of projects and documentation.
I think that each title could be considered a very huge contribution for every Open Source project that is involved in a similar work.
Consider that some of the material that is excluded from a book, because there are some constraints in terms of number of pages for each chapter, it is tipically used in the documentation of the project as a contribution.
For all of you that have a registered account in the Packt website will be a special gift for you during the next days. So if you don't have an account don't hesitate to create your Packt account!
For more information about this special celebration, please visit the official announcement.