People really expect the subs to work they way they do now though, so it's not likely to be changed until perl6 at the earliest. Imagine how much code would break if they suddenly worked differently?

I don't believe I am suggesting that existing "subs" work differently. What I proposed was the ability to declare a sub with "my" just as one does with variables. Do you think that if people saw:

sub print_sum($$) {
    my ($x, $y) =@_;
    my sub adder {return $_[0]+$_[1] };
    printf "sum of $x, $y = %d\n", adder($x, $y);
}
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That people would get confused about why "adder" would be used as a helper function to the main sub "print_sum"?

Is there another possible meaning of "my sub" that would be confused with using it to specify that sub is local to the block just like the variables are?

I'm not entirely clear about the term 'lambda'. Something to do with anonymous functions in lisp? I don't recall seeing it in the perl docs I've read (doesn't me an it's not there...just don't recall it! :-)).