One of the most common questions I'm asked is, "Is meta data still useful?" To which my answer is an ambiguous, "No!" Let me qualify that a bit...
For SEO (search engine optimization) purposes, yes, they truly are dead. At least from Google's point of view. And, I would say, the other 2 biggies in search - Yahoo and Bing - would be right behind Google (albeit a long way behind!). Have a look at the video below from the head of Google's Webspam team, Matt Cutts (you can also look at his blog here). He is VERY definite about Google not caring less about how many hours you've spent crafting beautiful meta tags.
That said, if you picked it up from the video, the description meta tag is still worth using, if only to entice potential visitors to your site. It's the one we spend the most time on to get right. As Matt said, this is the one that, if it seems to state really well what the page is about, that Google will display as the snippet in an organic search result. This can be very important to give the potential visitor a taste of what they can view. To hark back to my radio days, it is called a "tease". You hear it from announcers all the time. "Coming up this hour...."
The other tag that we will sometime spend time crafting carefully is actually the meta keyword tag, but only in certain circumstances. The time we would use this is if we utilize the "Related Content" module on a website. Where a site is really big, it's sometimes nice to show visitors what other pages have relevant or related content on them. The "related topics" modules use the meta keywords assigned to each page to accomplish this. But, other than this circumstance, and the description, we prefer to spend our time on important SEO tasks such as link building and keyword tracking. Ones that will really move you up in the rankings.
