High precision timestamps in Perl5/Perl6?

Why does Perl5 and Perl6 chop off a digit of precision on a high precision time call?

use strict;
use Data::Dumper;
use Time::HiRes qw( gettimeofday );

print gettimeofday() . "\n";
printf("%f\n", scalar(gettimeofday()));

Produces:

1243793974.02361
1243793974.023704

And, in Perl 6...

say time();
printf("%f\n", time());

Produces:

1243794052.38889
1243794052.391031