The short answer is - Yes! thats a promise.
The Spicebird source code is released under the same license terms as the Mozilla Firefox and Mozilla Thunderbird source code. We did that not as an obligation, but to make sure that all our work can go upstream without much trouble with the licenses.
Spicebird would be an open source project in it's true sense. The community will be involved in decision making and in the development of this project. We welcome contributions from the user and developer community in the form of feedback, bug reports and patches.