Opensource showcase for MVC in Java Swing

In my opinion, a full blown app would be more complicated to understand if you are struggling with basic steps.

Having said that, if you are comfortable with individual pieces, perhaps, you can look at different frameworks/tools which assist you in taking over the plumbing and you focus on the business aspect of things.

For instance, there is the

• Swing Application Framework (not sure about its current status) http://java.sun.com/developer/technicalArticles/javase/swingappfr/
• Use Netbeans as a platform, an example is available at http://netbeans.org/kb/70/java/gui-db.html. Another example with hibernate is available at http://netbeans.org/kb/docs/java/hibernate-java-se.html. Full list of examples are available at http://netbeans.org/kb/samples/.
• Ecplipse also has a similar facility where you can use it to develop desktop apps.
• You can also use code generators/frameworks such as Hibernate/JPA (for ORM), Spring (for misc things), or mix and match things.

In the end there is no "right" way to do something. If you are exploring, perhaps make a list of whatever you read. Explore them one by one. Do a simple todo application, and figure out what benefits/pains you encounter. Even modelling a simple app, will allow you to think about different things.

most Swing-resources don't implement the MVC-pattern

I am surprised you suggest that. Frames, Panels, Text Components are excellent examples. Perhaps it is worth mentioning, that swing library does not only use the MVC pattern. It also uses a bunch of other patterns, so this might be the source of your confusion.

Wrapping up, I would say, majority of applications could do with some sort of library which handles the windowing/other boiler plate, so you hook your code and are up and running fast. I personally use Netbeans as my IDE, and it allows me even to generate a sample CRUD database application (provided you have a schema). You can use it to prototype and tweak things as you like.