Google Comes Clean

Google has officially announced that it doesn't take any notice of your meta keywords. It’s been a suspicion amongst SEO specialists, including ourselves for many years but Google has finally given a small official insight into how their search engines work.

About a decade ago, search engines judged pages only on the content of web pages, not any so-called "off-page" factors such as the links pointing to a web page. In those days, keyword meta tags quickly became an area where someone could stuff often-irrelevant keywords without typical visitors ever seeing those keywords. Because the keywords meta tag was so often abused, many years ago Google began disregarding the keywords meta tag.

http://googlewebmastercentral.blogspot.com/2009/09/google-does-not-use-keywords-meta-tag.html

Of course other search engines may still use them and they do so is there any harm in using them? If you do make sure they are short, concise, and the keywords are also present in the page so they don’t look artificial.

You might want to keep using them to assist with site search - i.e. add keywords that your visitor might use to search within your site that don't appear in the page's content. (e.g. acronyms, speeling mistakes )

You might want to stop using them if you've done lots of keyword research that your competitors will benefit from when they look in your page's source.

The other meta fields (title, description) are still very important to SEO so make sure you fill them in on each page of your site.