I get asked at every single SEO conference or talk I do whether or not you should optimise your META tags. Firstly here is my answer:
Title tag <title> – Definately. Probably the most important factor in your SEO
META Description and Keywords tags <meta> – Yes. My reason for this is that although it may not be the most important tag right now it is still a fundamental tag which Google may use more in the future. Below is Matt Cutts (Head of SPAM at Google) view on this.
Matt Cutts on Toolbar Data » Online Marketing Blog: “Let’s take the example in a different context. Meta tags got a bad rap in the early days of search engines because a few people abused them heavily. As a result Google doesn’t use meta tags much in ranking documents. But I’ve learned not to say “We would never use meta tags” because it’s not wise to preclude using any particular signal; in the future, someone might work out a way to use that signal.
So I’m not going to say definitively that Google doesn’t/won’t use toolbar data (or other signals) in ranking. I think what you were picking up on was my long list of “cons” in data like that.”