The article says the feature has been removed; if it was the disk format:
1) it has never been removed, afaik Word still uses OOXML, so Word would keep being infringing
2) LibreOffice would probably be infringing too, as ODF is also XML based
So... it has to be some other form of XML tool and not the file format.
As for Joel's comment, IIRC he was an Excel PM before OOXML; in any case his blog post refer to the binary format that precedes OOXML.
I'm pretty sure OOXML is equally if not even more complicated, as the product themselves are way more complicated than they appear, but the fact is that he was talking about a different thing.
Edit: as many users pointed out, it's not the file format itself, but the ability to add arbitrary attributes/elements to the file format XML as additional data.
1) it has never been removed, afaik Word still uses OOXML, so Word would keep being infringing
2) LibreOffice would probably be infringing too, as ODF is also XML based
So... it has to be some other form of XML tool and not the file format.
As for Joel's comment, IIRC he was an Excel PM before OOXML; in any case his blog post refer to the binary format that precedes OOXML. I'm pretty sure OOXML is equally if not even more complicated, as the product themselves are way more complicated than they appear, but the fact is that he was talking about a different thing.
Edit: as many users pointed out, it's not the file format itself, but the ability to add arbitrary attributes/elements to the file format XML as additional data.