Ok... now I've been looking at this code for a while and created a makeshift plugin that does what I want (though I don't know PHP or s9y). On the blog linked to above my solution is the lower of the two week lists.

The problem with the links outputed by seems to by in serendipity_archives_plugin ...

Hi! I'm working on setting up Serendipity for a blog that needs to list postings by week, but I'm having problems with the "View by week" archive display. Postings appear to be from one week later than they actually are.

The site is here:
http://www.mcxl.se/serendipity/

Postings made today (which ...

Ok, just found out that can be done from the administration page...

Oh thanks, that works great!
Now is there any way I can get a list of weeks instead of months in my archives menu in the sidebar, so that it looks like:
* Week 40
* Week 39
* .....

I need to be able to view entries by week on my blog, and from what I've read there should be a "View by Week" archives display since version 0.8, but I haven't found any doc on how to use it.
Any idea how to do this?