OpenStreetMap OSM has gained a certain critical mass over the last few months. In many parts of the world, it is the best base map available. That's particularly true during disaster response: you just need to look at the OSM map of Haiti to understand this.
At present, OSM is becoming associated with 'open source' since many of the tools used to maintain OSM are open source tools.
Yet ArcGIS professionals have much to offer OSM. They have the knowledge to refine content, to transfer appropriate content from the Geodatabase into OSM. They have the world's best editing environment. I'd like to see the ability to apply these editing tools to OSM.
So a desktop user should have the ability to view a service of OSM as a layer in ArcGIS desktop. They should be able to select features from their Geodatabase and then copy them into OSM. These features should then be able to be snapped into existing OSM content. Where an ArcGIS professional wanted to refine someone else's contribution, they would be able to select the OSM feature and then interact with the OSM vertices.
Some might see OSM as a 'threat' to the Geodatabase or to ArcGIS Online content. Sure, there are overlaps but mostly I just see synergy. If ESRI technology can be used by ESRI users to contribute to (and then benefit from) OSM then everyone gains: OSM gets better faster (with all the huge benefits during disaster response); ESRI users get to benefit from the unreservedly free OSM; and the overall ArcGIS experience gets even richer.
I think there are other connect points between ArcGIS and OSM but for now, the Desktop editor would be a great start!