InfoPath Dev

Is there a way to use and code and rules in infopath?
The thing we want to is this:

we have a button, when you press said button you automatically save the doc at the right location. we do this by defining a rule, not that hard.
But that button also has to manipulate some strings (replace, concat, ... ) and we would like to do this in C#. Is that possible? Or is there another solution?

You actually can call code functions from rules. Here's a blog post on that by the InfoPath team -- it is actually a pretty cool and not too difficult technique.....