PDE in Eclipse 3.5 has a new enhancement to export source bundles. Earlier you could only include the source code inside the bundle. But now the source code can also be exported as a separate bundle. Eclipse can recognize it and associate it with the binary bundle. The source code bundles are very easy to identify for they have source in their name. A plug-in org.my.plugin_1.0.0 will have the source bundle as org.my.plugin.source_1.0.0.
The export process remains the same. But now you have a combo box where you can choose how you want to include the source code - Inside the bundle or as a separate bundle.
The source bundle option is available while exporting plug-ins as well as for features and product projects.