Apple is allowing users to download a free trial version of iWork ’08 that works for 30 days. Evidently its support for OOXML is read-only, and not complete at that. This means, to be explicit, that you can read some OOXML documents but not write them out again. I suppose this has the advantage of getting documents out of OOXML format (grin), but it is by no means “complete and accurate support for the full 6000+ page OOXML specification.” (Those are my words, by the way.) I reckon it’s not worthless to some, but it’s not like it is a bold interoperability statement either.
That said, iWork should support ODF. There is a petition to Apple to suggest just that.
Update #1: I tried opening Microsoft’s sample .docx file just as the person did in the link above, and I had no luck as well. I was told that it was not a Word file. There was no option available to either Save As or Export a document in OOXML format.
Update #2: I was told in a comment to another post that those sample files were out of date, even though they came from an official OOXML developer web site. That evidently explains the problem with opening them.