Hey, I just removed the pre stuff from a pre-Christmas 2.1 GitHub build, and it does code tags just fine in FF.
It's just using this:
array(
'tag' => 'code',
'type' => 'unparsed_content',
'content' => '<div class="codeheader">' . $txt['code'] . ': <a href="javascript:void(0);" onclick="return smfSelectText(this);" class="codeoperation">' . $txt['code_select'] . '</a></div><code class="bbc_code">$1</code>',
// @todo Maybe this can be simplified?
'validate' => isset($disabled['code']) ? null : create_function('&$tag, &$data, $disabled', '
ETA: Fine in Opera too.