This news has really made my day. The licence may not be truly open source, and all of the details may not be available yet, but what does seem clear is that the source code for many of the RISC OS components will be available for everyone to access for the first time.
It'll be great to have the opportunity to look at and change the underlying functionality of the OS. This opens up a host of possibilities
You look at many of the suggestions people made under the Merlin scheme or have made on the Iyonix list, and whereas before people had to speculate as to how things might work, it will hopefully now be possible for people just to go out and try things.