Microsoft announced in a blog post today
that it plans to release the documentation for the .PST file format in an effort to support interoperability. The .PST files are used to store various types of data, such as email, calendar, and contacts in Outlook Personal Folders. Microsoft wants vendors and customers to be able to access the data in .PST files on a variety of platforms, so developers can read, create, and interoperate the information stored within.
While Microsoft is just getting started on the documentation, the company is working directly with industry experts and customers to gather feedback to ensure that it is clear and useful. When the technical documentation is complete, it will be released under their Open Specific Promise, which will permit anyone to implement the .PST format on any platform and in any tool, without having to contact Redmond or worry about patents.