gkrellweather-2.0.8 does not work correctly (temperature data does not get updated), when gkrellm is run in a terminal it complains that /usr/bin/GrabWeather2 does not exist. It appears that this file is now installed as /usr/libexec/gkrellweather/GrabWeather, but something in gkrellm or gkrellweather still tries to use the file. Making /usr/bin/GrabWeather2 as a link to /usr/libexec/gkrellweather/GrabWeather resolves the issue and the temperatures are updated again. This is of course a hack, a proper fix is needed.
This particular bug can be closed since the "current version" of gkrellweather behaves properly.
Thanks a lot for the feedback