I encountered a few problems with the static publisher extension. Nothing major but here it is:
I created a page with the title images. When I then run /dev/buildcache?flush=1 the script fails at the page images and for some reason is trying to find a template Image.ss (but no page requires an Image.ss template, and all pages are the standard page type).
Recently I also get a message that the header was already sent when the static publisher script comes to the sitemap.xml page. I'm using Silverstripe 2.3.1 . I don't think I had that problem before in SS 2.3.0.
For now I just renamed the 'images' site to something else and removed sitemap.xml from the $urls array.