With the announcement that Microsoft is going to be working to provide some support (via third parties) to ODF we're seeing the same openness of the web translate into the desktop. As readers here know, I think the desktop as an application platform is an old model that won't survive the end of the decade in its current form. But Microsoft's Office suite is something that is still very entrenched in corporate America. The decision to incorporate some level of ODF into Office is a huge boon for RIA developers.
As our web applications start to look like desktop applications, we need to have the same kind of openness for the desktop that we have for the web. The tools that business users are working with every day can't be replaced overnight, but if you make sure that they can access their data - and they don't see any change in how their documents look - then you will be able to focus on the things that RIAs do better: cross-platform, web accessible, ubiquitous and tiny. Bring the openness of the web into the office and RIAs will be in a position to take advantage of it.