As suggested in one of the comments to my post I filed a bug report against Maemo, bug 6087.
Besides getting quite a few replies to the bug report within a matter of hours Carsten Munk pointed me at Maemo SDK+, which has less restrictive licensing.
Another comment, by Marius Gedminas (thanks!) pointed me at Mer,
a new operating system for small, mobile touch-screen devices.
It is Linux based and layers the best open-source elements of Nokia's Maemo platform over a modern Ubuntu base.
The goals of Mer include:
- Integrate the best solutions for a wide variety of small form-factor devices
- Encourage wider access to device capabilities through the Vendor Social Contract
- Demonstrably provide an easy route to market for vendors
- Dramatically reduce costs to vendors of supporting EOL hardware
- Focus, harness and support community contributions to the platform
- Encourage and ease migration of existing applications
- Support experimentation, innovation and development