If you happen to believe that the client-side XSLT transformations are a good thing (I am firmly footed in that camp), Firefox 3.x brings nothing but disappointments. Now it's Firebug's turn: they’ve managed to mangle the console.log function. It worked a while ago, but then a brilliant mind decided to re-implement it with a hidden DIV between the HEAD and the BODY element:
<div id="_firebugConsole" style="display: none;" FirebugVersion="1.4.5"/>
This DIV is created automatically for regular (X)HTML pages, but not for XSLT-generated content, so the output of console.log gets sent to /dev/null (plus you get loads of weird error messages).