You can't change a hash key, so you're better off just doing your stripping when you build the first hash. It's not a one-liner solution, but I often use bits of code like these:

# If I need cleanup only in one place, or want a special cleanup:
my ($key, $value) = map { s/\s+$//; s/^\s+//; $_ } ($orig_key, $orig_v
+alue);

# If I need to clean strings frequently in a program:
my ($key, $value) = map { clean_string($_) } ($orig_key, $orig_value);
sub clean_string {
    my $orig = shift;
    $orig =~ s/^\s+//;
    $orig =~ s/\s+$//;
    # ... other cleanup you want ...
    $orig;
}

# Alternative:
my ($key, $value) = clean_strings($orig_key, $orig_value);
sub clean_strings {
    my @a = map { clean_string($_) } @_;
    return @a;
}
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Disclaimer: Just junk off the top of my head, untested, use at your own risk, if it breaks you get to keep the bits, etc.

...roboticus