Be already makes publicly available a great deal of source code to the BeOS, for the purposes of documentation, instruction, sample code, etc.
Indeed, we fully intend to release as much source code as makes sense, to make it easier for other, outside developers to write applications, drivers, add-ons, and other software for the BeOS. We find that releasing good example code "jumpstarts" development in that area, which obviously we think is a good thing.
We do not, however, have any plans to release the source code to the core operating system. Open source has its place, and can be extremely valuable for some kinds and niches of software (it's done amazing things for Linux), but for a variety of reasons we believe it is more advantageous for the BeOS to remain proprietary at this time.