OLPC growing pains
The entire OLPC team is interested in supporting outside developers. There's no question about it, and there never was.
What's also true is that -- so far -- we've been building a platform (both Sugar and the distro) with heavy low-level development taking place in parallel with high- level activity development. This is tricky, with the usual resource constraints and timelines. As a result, we haven't been as good as we could be about leveraging the community and outside developers. This should improve as underlying platform development begins to stabilize and our focus turns increasingly towards activities and other consumers of our platform and APIs.
Communities are springing up in many languages and places; feel free to join one and get involved where you see fit; or to list your own groups there.