In the past, one gripe BlackBerry developers have had was the fact that RIM had too many devices with too many different screen sizes making it harder to develop apps for. That will end with the release of BlackBerry 10 as they will be standardizing the screen resolutions across the board. Now, instead of having to create different builds of an app for a large range of devices, developers can concentrate on the two outlined today however, as confirmed in the post the first BlackBerry 10 full touch device will be 1280 x 768 just like the BlackBerry 10 Dev Alpha is right now:
Of course, any developer who has been following BlackBerry 10 info knew this was coming but it's great to see it laid out for developers ahead of schedule allowing for any possible changes to be made in the evelopment process well ahead of time. Tim Neil has outlined the whole situation on the Blackberry Developers blog should you need more details and as noted, Developer tools will be updated whenever and however it is possiblle to do so.
Source: BlackBerry Dev Blog