I use the Slideshare plugin a lot on my blog to embed presentations.
I have just upgraded both my blog to 3.1.2 and the plugin to 1.8 and as a result the embed code/line no longer works.
For example see
http://elearningstuff.net/2011/03/07/embedding-web-2-0-into-the-strategy/
Screenshot
I have reinstalled the 3.1.2 update.
I have also deleted and reinstalled the Slideshare plugin.