Francois Zaninotto has posted a (large) new tutorial to his blog today detailing the forms functionality in the symfony framework.
Dealing with the display of form inputs, the validation of a form submission, and all the particular cases of forms is one of the most complex tasks in web development. Luckily, symfony provides a simple interface to a very powerful form sub-framework, and helps you to design and handle forms of any level of complexity in just a few lines of code.
The tutorial goes from the basics - displaying a simple form - out to complex multi-validations on the entered values.