to reply to my own post again - I did find a workaround now.
If setting the system language to English (instead of the default German) the iSync Conduit is visible and can be activated.
Note that the language has to be set to English during hot sync, too, otherwise iSync will not work.
Seems to be some localization problem. As the last posters which reported the problem are all from Germany or Switzerland, they may have the same problem (which may be unrelated to the original problem).
I found a better workaround now:
cd /Library/Application\ Support/Palm\ HotSync/Conduits/Apple/Contents/Resources/
sudo mv German.lproj German.lproj.original
After that, the conduit is visible and works if switching it on (though I have no idea why).
As there is only an empty resource file under German.lproj, this shall have no other side effect. If you have another than German language set, you may have to to change the respective path instead.
Danke für deine Antwort. Leider bin ich nicht so firm mit der Computersprache. Kannst Du Deine Lösung nochmal "idiotensicher" erklären?. Bei cd/ weiß ich schon nicht was Du meinst. Vielen Dank für Deine Hilfe, Gruß Kim.
sorry for the too technical answer...
What I meant is: start a Terminal (under utilities) and type in (or copy) the following 2 lines:
cd /Library/Application\ Support/Palm\ HotSync/Conduits/Apple/Contents/Resources/
mv German.lproj German.lproj.original
This just renames a folder.
You can do this using the finder, too: Navigate to Library -> Application Support -> Palm HotSync-> Conduits, choose "Show package content" in the context menu of "Apple", in the new window navigate to Contents-> Resources and rename the folder German.lproj to something (like German.lproj.orig), or if you are in France, do the same to French.lproj.