There has been a bit of a slight deceleration in the growth of Marketplace recently, with certified apps decreasing from 300 per day around December to 250 per day, but it turns out that this may not have been due to lack of enthusiasm by developers, but due to certification delays by Microsoft.
In Microsoftâ€™s Registered Developer Newsletter they write:
App Certification and Ingestion Delays
We are aware and are tracking delays in the app certification, ingestion and publishing process. Testing is currently taking 24-48 hours and publishing an additional 24-48 hours. Thank you for your patience as we work to clear the queue and scale to handle the high volume of submissions.
If Windows Phone will ever get to play with the big boys the certification process, already somewhat shaky, will have to deal with numbers 3-4 times bigger, so hopefully Microsoft is investing wisely in the system, especially given how essential the smoothness of the process is in keeping developers on the platform. We have seen for example the Carbon Twitter team nearly giving up on Windows Phone 7 after repeated certification delays, and I am sure we will all agree that would have been a major loss.