Quoting from there website:
The Department of Commerce’s United States Patent and Trademark Office (USPTO)
has created a partnership with the open source community to ensure that patent
examiners have access to all available prior art relating to software code
during the patent examination process.
It also indicates that releasing open source software with, or announcing it on, such an authoritative website is important! Otherwise, patent offices will not be able to decide wether our open source art is really prior.