Stuff in the java.lang.System class is pretty much the first defined in Java, and it predates java.lang.Arrays. I think because it came out first it is now pretty fundamental to so many Java programs that there is little chance for Sun to deprecate it.
There may well exist some "historic" reason for it (e.g. something in the C or C++ programming language standard library with the same name and a similar function), but I'm not aware of such a thing.
I'd guess that someone just wasn't following the current naming conventions, and then it was too late to change, without affecting substantial existing code. [ May 27, 2004: Message edited by: Dirk Schreckmann ]