Developers can download to a Windows PC Microsoft's Visual Studio 2010, Silverlight 4 multimedia toolkit, and the just-announced beta release of Expression Blend 4, a GUI-oriented design and code-generating toolkit. All come with an emulator running the full operating system, so developers don't have to wait for the first hardware devices, which could appear in October.
Developers with existing experience with Microsoft's PC tools can at once be productive in shifting applications to the phone or building new ones, including games with the new XNA Game Studio 4. Microsoft executives recited the mantra that developers can build an application once and then run it, with some minor adjustments for resolution and other features.
But many questions were left unanswered during an opening session at the event, including how Microsoft will structure its online Windows Phone marketplace, where developers can publish and sell their applications. Also unclear is exactly how developers can integrate their applications with WP7 hubs, which are visual locations on the user interface where like content is grouped, such as photos or music, and common tasks and features are enabled.
Such integration is possible, demonstrated by a number of new third-party applications demonstrated on stage.