At present there is no simple section to section navigation in the core moodle 2.0.
If you are viewing one section there is no easy AND quick way to get to another.

A fix for Moodle 1.9 is described here (http://www.youtube.com/watch?v=3pPnorX_Wus), based on a Section Menu from way back. This has a Menu block Plus a Single section format.

Rationale for why this is needed:
a) In a course, users want to go quickly from section to section, not course to course.
b) Avoid the scroll of death.
c) General experience shows this is an easy way to progress quickly on a usability issue. (IMO)

This proposal is for totally 'standard navigation' - not an odd type of section > section movement.
Needs to be simple to implement. (ie not to create this type of navigation with HTML blocks of tables in the section 0)

For 2.0 a solution has been coded by Lei Zhang
GITHUB: https://github.com/leizhang/moodle-block_menu_site_and_course
https://github.com/leizhang/moodle-course-format_sections

This suggests section 0 as a 'home page' for the course.