Google has released a new Webmaster Help video featuring Matt Cutts talking about duplicate and unique meta descriptions.
Cutts answers this submitted question:
Is it necessary for each single page within my website to have a unique metatag description?
"The way I would think of it is, you can either have a unique metatag description, or you can choose to have no metatag description, but I wouldn't have duplicate metatag description[s]," Cutts says. "In fact, if you register and verify your site in our free Google Webmaster Tools console, we will tell you if we see duplicate metatag descriptions, so that is something that I would avoid."
"In general, it's probably not worth your time to come up with a unique meta description for every single page on your site," he adds. "Like when I blog, I don't bother to do that. Don't tell anybody. Ooh. I told everybody. But if there are some pages that really matter, like your homepage or pages that have really important return on investment - you know, your most featured products or something like that - or maybe you've looked at the search results and there's a few pages on your site that just have really bad automatically generated snippets. We try to do our best, but we wouldn't claim that we have perfect snippets all the time."
No, believe it or not Google is not perfect (as Executive Chairman Eric Schmidt also reminded us).
Cutts concludes, "You know, in those kinds of situations, then it might make sense to go in, and make sure you have a unique handcrafted, lovingly-made metatag description, but in general, rather than have one metatag description repeated over and over and over again for every page on your site, I would either go ahead and make sure that there is a unique one for the pages that really matter or just leave it off, and Google will generate the snippet for you. But I wouldn't have the duplicate ones if you can help it."
Some will probably take Matt's advice, and start spending a lot less time bothering with meta descriptions. Just remember that part about looking at the search results and making sure that Google isn't displaying something too weird, particularly if it's an important page.