grouping tasks/cases within a project

Can cases be grouped within a project? This seems like it would be a standard use case. If a project is "build a website", it will have so many tasks/cases that they should be arranged in groups, like planning/development/theming etc. Right? I can't figure out a way to do this nor can I find any mention of it. I'm stumped cause this seems like it would be a very/universally common feature that people need... so I'm probably missing something.....?

The question is project-specific grouping. I'll probably create a generic taxonomy to be applied to tasks within a project type, but it'd be very cool if each project could have its' own grouping of tasks, it's own vocabulary perhaps (that gets automatically created when the project is created - Rules could do this maybe?), or if there was an ad-hoc grouping option like the way Basecamp offers "task lists".