There exists plenty of documentation on the web on adding points and polylines to google maps, but very little on how to add polygons. I hope this documentation will be useful to others as it can take quite a while to figure all of this out (as I found out). This documentation is meant to be used in a windows environment running php on command line. If you know of any other methods to add polygons, please let me know, but so far this is all I've been able to find, other than the following site that lets you load a shapefile for a one time only map http://www.wildsoft.org/surveyarea/map/map.aspx.
1 - Here are the steps required to add shapefiles or mapinfo (*.mif) to your google maps. If you have google maps installed on your server already, skip to step 3.
3 - Ensure that php is running on your server or your desktop (in this case you only need php to run one processing script). If php is not installed, installs are available from www.php.net (including command line for windows). Help with running a php script is also available on this page.
4 - Get mif2gmap.php script from http://www.fightthebite.net/mif2gmap/mif2gmap.zip and unzip the files in a directory (your choice).
5 - Edit the index.php script to suit needs (ie. change your google API key to the one for your site, set the center of the map to the coordinates you want to center your google map on, title of the web page you're creating, etc.)
6 - If using shapefiles, convert your polygon shapefile to mapinfo (mif) format using either FME or other GIS tools such as the free ones found at fwtools.maptools.org or freegis.org
7 -Place *.mif files in the "MIFs" folder (without quotes) where you unzipped mif2gmap.zip
8 - Run index.php script in the following manner
"index.php > nameoffile.html"
(without quotes) where "nameoffile.html" (no quotes) is the file you want to create with the polygons attached to your google map
9 - Place "nameoffile.html" (no quotes) in your web space
11 - Edit and customize your new maps as you see fit. Note, the php script was written by Matt Farley. His web page can be found at http://www.farleyfamily.net/
This page: http://www.library.utoronto.ca/maplib/googlepolygons.html