Check out this video with Matt Cutts, Google Software Engine. Google does not consider META Keywords for ranking pages at all.
However, it is important to attend to your META Description tags as these make an impression on customer prospects in the search results. A META Description that uses relevant and meaningful copy can impact a search engine users decision to click.
The basis scenario is that of a website owner sueing a competitor who practiced black-hat SEO method of including the competition-name as a keywords in their META Keywords tags. Under these conditions, Google states that they do not consider the META Keywords tag for ranking websites.
But this video is the final nail in the SEO coffin of META Keywords
On that note, focus on your customer's needs. Publish valuable content relevant to your visitor's needs and pursue effective functionalites that empower your visitor and improve the usability of your site. Content is King. Usability is Queen. META Keywords are just for Fools.