Microsoft has reduced the annual sign-up fee for its Windows Phone Developer Center from $99 to $19. It now looks as though this is a permanent change.

During August Microsoft ran a "Summer Break" promotion, offering Windows Phone developers $80 off the normal annual registration fee. This attractive deal had been scheduled to last only until August 27 but instead of ending it, Microsoft has decided to let the lower sign-up fee continue. We can only conclude that making joining the Windows Phone developer community more affordable had been a success in terms of encouraging devs to do so.

The news of the extension to the promotional fee came in a tweet from Todd Brix and is prominently displayed on the Dev Center itself which has undergone a face-lift and is looking upbeat and active.

If Microsoft is to succeed in its transition to becoming a devices and services company, it needs to break into the mobile market and attracting, and retaining, third-party developers is obviously important. Let's hope that the lower fee indicates that it now understands that it needs to recruit enthusiastic developers rather than make them pay over the odds for taking the time and trouble to create the apps that are needed for success.