Agrees with the answers.
You need to know what you want to achieve.
1. Application (registration processes, business logic, multiple way to show data (webservices for instance))
... best suited for a Framework
2. Website (show pages, basic lists (simple joints))
... best suited for a CMF or a CMS (CMF is what MODx is with symfony for content... than what WordPress is for a blog)
3. Blog (Frequent posts, categorization, comments, basic CMS)
... WordPress. No question.
4. Build an open source application
... please. use a framework!! pls.
my two cents