It may be a sign that none of the core WordPress developers much likes or uses Microsoft Office, but the core code hasn’t been updated to recognize the Office 2007 file extensions like
.xlsx. It’s no criticism, wouldn’t have discovered it if a user hadn’t complained, and I stewed a bit before deciding it was a bug.
It’s now ticket #8194 in the WordPress.org Trac. It only affects my MU users now, though, and the same patch works there.
You’ll find a few mentions of
wp-includes/functions.php (around lines 1613-1615 and 1651-1654 in 2.6.3). Once corrected, those lines should look something like this:
'document' => array('doc','docx','pages','odt','rtf','pdf'), 'spreadsheet' => array('xls','xlsx','numbers','ods'), 'interactive' => array('ppt','pptx','key','odp','swf'),
'doc|docx' => 'application/msword', 'pot|pps|ppt|pptx' => 'application/vnd.ms-powerpoint', 'wri' => 'application/vnd.ms-write', 'xla|xls|xlsx|xlt|xlw' => 'application/vnd.ms-excel',
Update: Sweet! It’s been accepted and should be in the WP2.7 release.