It's not a problem actually, more a request from the wordpress Team.
Regarding embedding, I'm aware of what is applicable (or "allowed" if this term is more appropriate) after reading this : http://en.support.wordpress.com/code/
Now, it would be great if the WordPress Team could allow code for embedding the "trip viewer" of http://spotwalla.com/index.php . A lot of people (including myself) that are involved in outdoors activities are using GPS tracking devices and spotwalla is a Secure Personal Location Manager that allows us to share our position via those devices. Spotwalla offer embeding, it is described at their site (link: http://spotwalla.com/help/trips.php#embedding) but unfortunately doesn't work with wordpress.com.
Blog url: http://roadspirit.wordpress.com/