Create a new metatag type with dynamic tag

Google announced that for sites that are Google News certified, they are going to use a new metatag that will actually matter. Great. So I need, for each post, to come up with a metatag that looks like this:

<meta name=”news_keywords” content=”tag1, tag2, tag3, tag4…”>

I know I’ll want to put this code in the header.php file, but I have no idea how to write the appropriate PHP code to take the tags of a particular post and have them appear as I want them to in the above example.

Any help? I will seriously pay someone a few bucks on paypal for helping if your code works ;P