Note that we are in the process of migrating from Trac on portaudio.com to Assembla. (1/24/12)
The SVN repository at https://subversion.assembla.com/svn/portaudio/portaudio/ is used by PortAudio developers to keep track of the source code. See the Wiki for full instructions on Using PortAudio SVN.
You can either log in using a SVN client on Unix, Windows, Macintosh or you can just download a tarball that is made every night from the repository.
Or you can browse the SVN repository online at: http://www.assembla.com/code/portaudio/subversion/nodes/portaudio/trunk