At the moment, when one puts the first part of a word between [[square brackets]], the word as a whole will become a link. Although I like that as a general principle, I think it would be good to have an opportunity to escape this, and give a possibility to have only the 'zoo' in [[zoo]]keeper be linking. This would especially be useful in a language like German, where complex terms are often formed by stringing words together into a single word, rather than in a sequence of words as is usual in English.
As a fellow German, I don't think it's necessary. Half-links (heh!) are irritating because they interrupt the reading flow and force the reader to mentally emphasize part of the word. They also encourage overlinking and lazy linking (the combination of which forms a condition commonly referred to as "Everything2 syndrome"). If you feel an urge to create such links, you're probably doing something wrong -- you should use "See also" instead or change the prose accordingly.
Regards,
Erik