Inserting meta tags into head

Hi,

I want to do something really simple, but it doesn't seem to be working. All I want to do is add some open graph meta tags to the head, and I tried adding them to the page.tpl with no luck.

Basically what I'm trying to do is specify some og tags, as here:

http://developers.facebook.com/docs/opengraph/

Also, I have tried the open graph meta tags module, and it doesn't output any tags - I am wondering could this be a theme related issue?

How do you add stuff to the $head using the page.tpl?

Many thanks, Joe