I have recently been interested in the early history of multidimensional array support in Python. Most of the early development was discussed on the Matrix SIG. In January 2000, the Matrix SIG was retired and further discussion moved to the numpy-discussion mailing list hosted at sourceforge. More recently the mailing list moved to the SciPy server, which is hosted by Enthought. The archive from 2000 to the present is here.
Unfortunately, the Matrix SIG archive (1995-2000) was missing. And had been missing since at least 2005 when Robert Kern noticed that it had disappeared. Thanks to Skip Montanaro, Brad Knowles, and Barry Warsaw the archive has been restored.