I am impressed with ‘s customer service. 

I got an email last night from them providing a workaround for the problem I detailed in my post on Wednesday, , a mere day later.  This is the solution they gave me:

At Weblogs > Posts, click on the title of the post to go to the Compose
page. Click on the "Customize the display of this page." link toward
the end of the page. Select Plain Text and click Save Changes. The page
will refresh and display only the HTML for the post which will allow
you to edit the post. Click Save changes when you are done editing.
More information is available in the .

When adding complex HTML, including embed code, to your posts, we highly
recommend using the Plain Text editor. More information on adding HTML
to posts is available .

It works perfectly.

The Google Maps embed code uses the , which I suspect is what is causing the problem in .