This is interesting: USPTO Statutory Invention Registration
Basically it's a way of publishing an invention to the public via the USPTO. Rarely used for obvious reasons.
Question #1: Why don't open source people apply for these USPTO invention declarations? It seems to be the patent law equivalent of a BSD/MIT license.. ie "use/extend it for any purpose but it's still my work and you can't claim it as your own work."
The more interesting tidbit on there is, while obvious, a potential source of great technical material. Since 1999 when you file a patent it is published 18 months after the file date. Once an application is abandoned the application and is published by the USPTO and it becomes public domain.
Question #2: Are rejected patents whose appeals have run out then public domain? I can't seem to find a clear answer.
How many rejected/abandoned software patents etc out there from Microsoft, Oracle, IBM, etc are there that contain very valuable algorithms and techniques that are now public domain? Yes this is a bit like looking for gold in the trash can...
The European Patent Office by treaty publishes many USPTO patent apps.. and honestly has a better interface for getting the status of your patent than I have yet found at the USPTO.
The Patent Reform Act of 2005 (Republican sponsored) was an attempt to close the publication 'loophole'. The Patent Reform Act of 2007 (Democrat sponsored) keeps the current publication system in place. Neither is law (yet).