SomaFM is a streaming radio with near 16 different channels, available for free. Even if it's possible to copy-paste their streaming URLs to N900 Media Player, we (me and Lorenzo Bettini) decided to create a custom application, to make channels switching easier for the end user and to be able to add more features. We decided to take advantage of the new Nokia SDK and write the application in Qt/C++. Source code is available on Gitorious and it's always updated with latest version we're working on. If someone want to test the application, it's available in extras-devel repository ("msoma" under Multimedia section) of N900.
The UI is still in development as you can see. The application is already usable, but of course we have to work hard on the user interface. Feel free to test/use it and send us any feedback. If you want to contribute to our project (coders are welcome) please send us a patch with your code or ask us to be added to mSoma development team in Gitorious.