iframes
 

If a page is only ever viewied in an iframe... does it count as a page (seo thinking here) or doesn't it?

I dont believe a search engine will see it. Unless there is a link to the page in the iframe. Search engines mainly just follow links, I dont think they will extract anything from an iframe, just put an href link to the page in the iframe if you want the SE to find it :)

A search engine will not read the contents of an iframe as part of the page in which it appears. Via the iframe source, it will read the iframe as a separate page and score it independently.

That can be a good or a bad thing, depending on the circumstances.