I'd put more emphasis on the fact that the first argument to split is always, always, always a regular expression (except for the one special case where it isn't :-). Too often do I see people write code like this:

@stuff = split "|", $string;            # or worse ...

$delim = "|";
@stuff = split $delim, $string;
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And expect it to split on the pipe symbol because they have fooled themselves into thinking that the first argument is somehow interpreted as a string rather than a regular expression.