There is lots of stuff about software patents (see http://www.gnu.org/philosophy/philosophy.html) - here is one issue that has come up for me recently:
Extract from Contributors License
Without limiting the foregoing representation, Contributor represents that, to the actual knowledge of Contributor as of the date of this Agreement and without implication of a duty to investigate, the Submission in the form provided by Contributor hereunder will not violate any third party patent, trademark or trade secret right.
As software developers, we know that the main problem with software patents is, any source code of significant size will violate a number of patents. Finding out which is difficult. Paying for them is impossible.