Why do you expect it to be there? In order for me to compile successfully the HelloWorldSWT class in Eclipse 4.2.0, first I have to add the SWT library into the project's java build path. After that the program runs fine on my F17 x86_64 system. In my 64-bit system, the SWT library is found in "/usr/lib64/eclipse/" folder. I believe they are there because of "eclipse-swt" package. Alternatively, use the SWT standalone download as recommended here
To run the Java class outside of Eclipse IDE, I use this command.
CLASSPATH=/usr/lib64/eclipse/swt.jar:. java HelloWorldSWT