http://en.wikipedia.org/skins-1.5/common/wikibits.js

function ts_getInnerText(el)

this function contains:
if (el.innerText) return el.innerText;	// Not needed but it is faster

innerText is an IE extension. In Safari 3 it seems that this function is also present now, but it behaves differently it seems. For instance

<td><span style="display:none">02005-06-02</span> <a href="/wiki/June_2"
title="June 2">June 2</a>, <a href="/wiki/2005" title="2005">2005</a></td>

in IE innerText will result in: "02005-06-02 June 2, 2005"
on Safari 3.0.2 i get: "June 2, 2005" (not returning the display:none text)
This messes up the sortkey trick used in en.wikipedia on for instance the dts template. Since it is only used for a speed increase i suggest to either remove it all together or alternatively, change it into:

if( is_IE && el.innerText) or something.