How can I disable relative dates in elements index?
Until this feature get implemented, I think I'll go with the following workaround that I'm using right now.
It's based on  getEntryTableAttributeHtml hook where I reformat the date value to match the user locale preferences.

public function getEntryTableAttributeHtml(EntryModel $entry, $attribute)
{
    if ($attribute == 'postDate')
    {
        $localeData = craft()-&gt;i18n-&gt;getLocaleData(craft()-&gt;language);
        $dateFormatter = $localeData-&gt;getDateFormatter();
        $format = $dateFormatter-&gt;getDatepickerPhpFormat();
        return ($entry-&gt;postDate ? $entry-&gt;postDate-&gt;format($format) : '');
    }
}


or simply

public function getEntryTableAttributeHtml(EntryModel $entry, $attribute)
{
    if ($attribute == 'postDate')
    {
        return $entry-&gt;postDate;
    }
}


which will return the date in Y-m-d format regardless of locale.