Okay, a really twisted way of getting the information.

The debugger extends what caller() returns if caller is called from the DB:: namespace:

$package: The package name the sub was in
$filename: The filename it was defined in
$line: The line number it was defined on
$subroutine: The subroutine name; '(eval)' if an eval().
$hasargs: 1 if it has arguments, 0 if not
$wantarray: 1 if array context, 0 if scalar context
$evaltext: The eval() text, if any (undefined for eval BLOCK)
$is_require: frame was created by a use or require statement
$hints: pragma information; subject to change between versions
$bitmask: pragma information: subject to change between versions
@DB::args: arguments with which the subroutine was invoked (which is what you want).

You may be able to do what you want by defining an xcaller function that does this:

sub callers_args {
    return DB::caller_caller(@_);
}

sub DB::caller_caller {
    my($level) = @)_;
    local @DB::args;
    caller($level+1);
    return @DB::args;
}
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This is of course pure evil. Localizing @DB::args may let you run this under the debugger, but be prepared for weird and wild situations. You may need to turn off single-stepping in DB::caller_caller if you do try running under the debugger using $DB::single.

Again, if you used this in production code, you would be completely mad. And of course the other consideration: if you need to do this, you're not thinking about the problem the right way. What really needs to happen - forgetting completely about the implementation?

(correction 12/5/08: formatting was awful. Bad perlmonk. No biscuit.)