There will be more details over the coming months on what's coming in Office 2010, and the power it brings to developers. I'm particularly excited to start talking about the ways in which you can combine the power of the rich clients with server side technologies to build solutions that no longer just target a specific individual using a specific application, but instead expand out to the workgroup, and all the content they are leveraging to accomplish their goals.
Many developers are already building solutions that benefit from the combination of SharePoint and the Office rich clients, and I wanted to make sure that folks were aware of the developer conference coming up this fall that will go into all the details of Office 2010. As Gray points out in his latest blog post (http://blogs.technet.com/gray_knowlton/archive/2009/05/30/office-2010-for-developers-office-developer-conference-moving-to-sharepoint-conference-2009.aspx), there will be a dedicated track at the SharePoint conference 2009 specifically focused on the rich extensibility model in the latest version of the Office client suite. Many of the features that provide immediate value to the typical end users also will allow developers to build some pretty interesting and powerful custom applications.
Also, don't forget to sign up for the technical preview!