Wim De Smet wrote:

recently I've heard somebody say that for software patents you need to submit the source code and therefore make it public.

That's not correct. As part of the patent application, you need to include a "complete description" of the invention, so that someone else is able to re-implement it. For software-related inventions, you typically do that with flow charts, pseudo-code and functional descriptions.

In fact, in Europe you're not allowed to include a complete reference implementation in the patent application. The EPO says:

In the particular case of inventions in the computer field, program listings in programming languages cannot be relied on as the sole disclosure of the invention. The description, as in other technical fields, should be written substantially in normal language, possibly accompanied by flow diagrams or other aids to understanding, so that the invention may be understood by those skilled in the art who are deemed not to be programming specialists. Short excerpts from programs written in commonly used programming languages can be accepted if they serve to illustrate an embodiment of the invention.

I'm rather convinced this is not right. Could somebody point me to some simple examples I can give, so I have more to backup my statements?

What exactly are you looking for? Examples of software patents? Or patents that include pieces of source code?

Regards,

Arnoud