Jachym:
> so, my question: is there such script already (maybe
> something in GDAL/OGR package, which I missed)? Isn't there
> any big mistake in my script?
to speed it up use v.in.region+v.select before v.overlay, so expensive overlay is only performed on relevant features.
during import you can replicate that with v.in.ogr's -r or spatial= options.
Hamish