I assume you’ve already dug through the Google Maps API documentation?
I’ve included a map in a WP page. It’s a static map that shows a number of points with lines drawn between them. The points and the info about them are stored in a db table. So my little script probably won’t help you that much. But this is what I did, more or less:
1) I got a google map api key.
2) I set up a template for my map page because I wanted it to be separate from my main blog.
3) I put a call to the google map script, including the key for my page.
4) I added onload="showMap();" to my body tag.
5) I replaced the loop with <div id="map" style="width: 820px; height: 700px"></div>
6) I wrote a script that reads the db table and plots the markers and lines on the map and stored it with my template.
7) In the footer of my template I include the script page.
8) In WP, I created a page using my template.
I’m not all that good at this, and may have done more than needed and may have done it in a hokey way. But it did work.
I use a couple of google map plugins on my site(http://cjw.me.uk), some of which might fit the bill…
Geo Mashup
http://www.cyberhobo.net/downloads/geo-mashup-plugin/
Adds a Google Maps mashup of geocoded blog posts. By Dylan Kuhn.
Inline Google Maps
http://avi.alkalay.net/2006/11/google-maps-plugin-for-wordpress.html
This plugin shows google maps anywhere on blogpage. By Avi Alkalay.