This survey of Belgian mobile developers found the following:
1) Most developers are hobbyists or work for startups, and are located in Antwerp, Brussels, and Flemish Brabant regions.
2) Developers make little money from mobile apps, usually less than $1000 per month as a hobby.
3) Top challenges are balancing hobby work with day jobs and technical/commercial uncertainties.
4) iOS, Android and HTML5 are the most popular development platforms, while Symbian and Java are declining.