I suspect that Java was intended to be a trojan horse to impose a new architecture. So the "write once, run everywhere" was soon dropped when Sun tried to peddle Java processor because it skewed the game.. Anyway Gosling himself has said that this portability was more a marketting concept than a real technical one;I can't find the reference though.

Once you have many implementations out there, even if everyone wanted to play honest to adher to the "Standard", there is always place fo incompatibility. Perl on the other hand is surprisingly portable for a language that had not initially been designed for portability or security . One strong point for Perl is that it is essentially one implementation portable across many operating system. This leaves less leeway for divergence!

-- stefp