Yet Another NULL Article
Interestingly, some of the people in this camp might be Oracle engineers. As Laurent Schneider has recently pointed out, Oracle have implemented different behaviour for LOBs. A zero length CLOB is not NULL. We could infer from this that, given the opportunity, Oracle might choose to treat empty VARCHAR2 variables this way too. Then again, it may just be an artefact of the LOB implementation. Either way. the upshot is that Oracle is unlikely to change the existing behaviour simply because such a change would probably break too many existing applications.
Of course, every languages have their quirks, especially with something as slippery as NULL. And developers in other programming languages do funny things with NULL, as this posting from the Daily WTF demonstrates.