I started rewriting this addon because I thought nobody had done it yet. I was mostly done when I found out that Dalai updated it already.
The problem was that the "make update" command always checks out the master branch of the addons repo without me noticing it.
In the master branch the addon was not updated obviously.
Anyway, because I was almost done, I decided to just finish my version because I think it works quite well and might be more maintainable.
Also this version produces better results when exporting as png.
The addon supports exporting the uv layout of multiple objects into the same target file.
I don't use a very advanced mechanism to decide which polygons to include in the export.
Basically either all polygons get exported or only the selected ones.
I think the method implemented by Dalai is overly complicated. If this functionality is really needed it should be part of some Blender API so that not all addons have to reinvent the wheel.