[Note: The issue I was dealing with has been obsolete since expandable posts became an integral part of Blogger. For more information, read this post.]
You have a blog on Blogger. You modified your template(s) for expandable posts. You start in "Edit HTML" mode and then switch to the "Compose" tab; when you go back, the and tags disappear. You type them back in. When you post your entry, it works just fine in IE, Firefox, Opera, and the like. Unless your browser is based on WebKit: that means, for example, Chrome, Safari, or Konqueror. (WebKit is a superset of Konqueror's KHTML developed by Apple for Safari.) Then the entry you just posted is expanded on your blog's homepage. Which, of course, you don't want. It's as if those <span> tags never existed for WebKit browsers.
(If this post is expanded on the front page, then you won't see this line.) [Note: this no longer applies. Read the post linked at the top.]
The result: You see this text on the blog's front page! If you're using a non-WebKit browser, you won't see it till you click the link to the rest of this post (or any of its other permalinks on the front page). But if you're on the front page and you see this text, you're using a WebKit browser for sure.
But is the glitch in WebKit, or in Blogger? In any case, it shouldn't be happening.
Is this happening to your Blogger blog? Go to http://webkit.org and tell them.