Programmers can either use the Swing components as they are, or modify parts of the model or delegate to greater deal with their needs. Swing also provides a rich text framework that allows programmers to do almost anything in six or seven lines of code. Also, there are some multithreading issues that Swing developers will face when working with the component libraries. Both are relatively easy to overcome and are covered in great detail in the book. Read Jonathan Knudsen's Soothe the Savage Breast article to find out how.
Source code is included.
Others will not. It's hard to gage which one's will right now. However, a great deal of effort has also been placed into optimization of the Swing components, as this has been a central issue since it first debuted almost a year ago. The benefits of using lightweight components clearly outweight those of the older AWT components. In the future, I hope to see many new components added to the Swing libraries.