SnowDrop is a project for reliable, difficult to remove watermarking of text documents (internal memos, draft research papers, advisories and other writing) and C sources (limited distribution software, licensed software, proof of concept exploits, or freely available code) so that: (1) leaks can be identified if the data goes public, (2) original source can be determined and demonstrated if part of the document is claimed by somebody else, copied without permission, etc. The project uses redundant steganography using four different logical channels, and should be prone to many modifications, including reformatting, spell checking and so on. Perhaps Microsoft should consider it for their internal memos 
You can check out the beta code here.