If your work is being done in a corporate environment – as most Linux kernel work is – you must, obviously, have permission from suitably empowered managers before you can post your company’s plans or code to a public mailing list. The posting of code which has not been cleared for release under a GPL-compatible license can be especially problematic; the sooner that a company’s management and legal staff can agree on the posting of a kernel development project, the better off everybody involved will be.
Some readers may be thinking at this point that their kernel work is intended to support a product which does not yet have an officially acknowledged existence. Revealing their employer’s plans on a public mailing list may not be a viable option. In cases like this, it is worth considering whether the secrecy is really necessary; there is often no real need to keep development plans behind closed doors.
That said, there are also cases where a company legitimately cannot disclose its plans early in the development process. Companies with experienced kernel developers may choose to proceed in an open-loop manner on the assumption that they will be able to avoid serious integration problems later. For companies without that sort of in-house expertise, the best option is often to hire an outside developer to review the plans under a non-disclosure agreement. The Linux Foundation operates an NDA program designed to help with this sort of situation; more information can be found at:
http://www.linuxfoundation.org/en/NDA_program
This kind of review is often enough to avoid serious problems later on without requiring public disclosure of the project.