tedster - 8:14 pm on Jun 21, 2011 (gmt 0)
Yes, it sounds like you're doing enough. However, I don't think Google is going to pay attention to the "expires" meta tag.
And sometimes, if you are expiring a very popular bit of content, a 301 redirect to another relevant page is a good idea - or even just changing the content on the existing URL to be informative and letting it stay as a 200 OK page.
It all depends on what you are offering and staying in touch with how it is performing.