I have the same issue <a href="http://en.forums.wordpress.com/topic/how-do-i-embed-iframes-in-my-posts?replies=10#post-930627
">as in not being able to embed a Google Doc PDF into a wordpress.com blog.
I have a PDF at Google Docs
That I want to embed, I followed the instructions here
I used this embed code
<iframe src="https://docs.google.com/file/d/1NeKEQyAJFiHuJs0AA1g14mgKMVMOxjxtSE32SfKh09rBptjLYnv9V2MX3k9o/preview" width="640" height="480"></iframe>
which do not seem to work for the PDF for me, simialry with the original author of the query and there seems to be no solution ? So I thought I would try other documents and they similarly do not embed (yes they are made public prior to copying the embed code from Google Docs)
So, it appears I can't embed any Google Docs. My questions are what am I doing wrong or if I am doing nothing wrong, what is WordPress.com doing wrong and is there a fix ?
The blog I need help with is goodwillcentersihanoukville.wordpress.com.