I have been experimenting with my Collapsed Topics format and created a hybrid based upon the weeks format.
It operates in exactly the same way as the topics version but always has the current week open when opening / refreshing the page.
If you want to try it, please install the attached by unzipping and moving the folder 'weekcoll' to your 'course/format' folder, then you will find a format called 'Collapsed Weeks' in your course settings.
Please note that this is the Moodle 1.9 version and is 'experimental'.
Comments appreciated

Cheers,
Gareth