There is also a wordpress plugin for adding this tag.
Press this is a interesting WordPress feature. It would be interesting to midify it i a way rhat one could “press” articles from any computer/browser without a full authentication. Kind of like a (semi-) public “Press This”.
This would be a nice project for my spare time.
I recently got into huge problems with iframes on WordPress. I tried a lot of things and was not really sucessfull. The background probably is, that wp tries to avoid any imput with the iframe tag. So, what happened to me was, that the admin user was able to create an iframe, BUT as soon as the html code of the post got updated by another user, the iframe was gone as if had never been there. So I propose using a plugin to input iframes with wp’s shortcodes (e.g. iframe).
A good help source for creating a custem WordPress plugin with a simple widget.
How to Create a Simple Custom WordPress Widget – JonLoomer.com.