While OOXML-compliant software seems conspicuous by its absence, ODF goes from strength to strength: there is literally no contest between the rival standards in this respect. That's not to say that there aren't still teething problems with ODF, with incompatibilities of varying seriousness showing up between alternative implementations. Here's a valuable new free service that should help. It aims to spot problems before you send out documents that might be viewed on different platforms. It's called Officeshots.org.