When I was at Symfony Live this
past February, I assisted Stefan Koopmanschap
in a full-day workshop on integrating Zend Framework in Symfony
applications. During that workshop, Stefan demonstrated creating Symfony
"tasks". These are classes that tie in to the Symfony command-line
tooling -- basically allowing you to tie in to the CLI tool in order to
create cronjobs, migration scripts, etc.
Of course, Zend Framework has an analogue to Symfony tasks in the Zend_Tool