Okay...we all know that google doesn't place much emphasis on keyword meta tags. My question is this, does the type and amount of keywords within the meta tag, come into play with overall keyword density within the page when crawled?
actually, google does see keyword meta tags as important (at least they did before jagger). the "webmaster" at my work (actually just a guy who is a much better programmer than he is at seo) accidentally deleted the meta tags from the company site, and our SERPs started dropping big time. once my boss chewed him out and had them replaced we went back to where we were before on the SERPs. just remember to keep your meta tags under 250 characters, and only use relevant terms which can be found within the content of your site.
You're assuming that a search engine even knows what the concept of keyword density is. As far as I understand it, each word occurrence in a document is counted, but I've not seen any evidence that a density is considered. Since you can easily spam the meta keywords tags I doubt that their contents are counted in the word count.