The Ovi Store has no problems in the publication and distribution of open source software per se. But in order to be approved as Ovi publisher you need to meet certain legal requirements usually not met by individual free software developers or even more complex projects handled by volunteers. In practice this means that open source applications don't have a simple way to reach end users via Ovi.
This might be a missed opportunity for open source software to get the acknowledge of average Nokia customers and to compete side by side with non-free / commercial alternatives.
Discussion: http://talk.maemo.org/showthread.php?p=385610