Though Microsoft pushed for fast tracking OOXML as a standard, they have shown no interest in supporting it in their own products even though it's something they created (and no one else wanted).
Link
Microsoft's failure to adopt the standard version of the format after two years has drawn criticism from Alex Brown, the convener of ISO's OOXML subcommittee (SC34).

"If Microsoft ship Office 2010 to handle only the Transitional variant of ISO/IEC 29500 they should expect to be roundly condemned for breaking faith with the International Standards community."
It is now abundantly clear that fast-track approval of OOXML was a mistake. By giving Microsoft the approval first with the intention of correcting the problems in the standard later, ISO eliminated the incentive for Microsoft to take conformance seriously. It is increasingly obvious that Microsoft only wanted to be able to advertise its format as being ISO-approved and never really cared about interoperability or actual conformance with the standard.
Sounds just like Microsoft's attempts at standards compliance in their browser. Always behind the curve. Last in implementation. Always fighting everyone else. Always on the other side of the fence from everyone else. They can't be trusted.