Interesting to see the Microsoft folks making a big deal out of the fact that companies are implementing OOXML features in their software products. I'd hesitate to join them being thrilled at IBM's new-found support for their strategy. Truth is, when there's a monopolist in the market it's impossible to ignore the consequences of even their worst ideas, let alone their good ones. Responding to the needs of locked-in customers who will find themselves using OOXML is a different deal to strategic support.
A much more crucial question, though, is why the folks at Microsoft are so surprised. If you know your customers have a requirement, surely you respond to it? The real question this situation brings to my mind is not "why are IBM implementing OOXML features". It's "why won't Microsoft implement support for ODF at least to the same level as RTF built-in to Office?" Given they have a number of very significant and visible customers demanding that support, it seems to me they are the ones with the explaining to do, not IBM, Google, OpenOffice.org or anyone else.