Meta Description Tag in SERPs

Recently we've noticed that the meta description in the SERPs seems to be changing. It's a little odd because in Yahoo the descriptions we're seeing, and also the page titles, are up to 2 years old! In Google what seems to be happening is that the meta description is only half being picked up and the rest of the description is coming from elsewhere on the page.

What we've also noticed is that this hasn't been the case for the first few results, but only for those listings that are lower down the first page. The first few results are still using the meta descriptions tag to populate the results.

As we all know, the meta description tag has not been used by search engines, specifically Google, for indexing a page according to specific keywords for a long time. Although there have been some discussions about Google starting to change their stance on this it would still hold true that they are unlikely to use this tag for the purposes of ranking a website according to specific keywords, in other words for SEO. However, it has also been common practise for the search engines to use this tag, when it has been properly populated on the website in question, for the description that shows up in the SERPS. For properly - and by this I mean non-spammy and at the correct length - meta descriptions it seems strange that they wouldn't use it for some websites and they would for others.

At a keynote presentation at the Search Engine Strategies (SES) Toronto conference in June 2010, Maile Ohye, senior developer programs engineer at Google announced that they have been placing more emphasis on meta descriptions. Again, this was not for SEO purposes but was for overall relevancy. Yet this seems to be the opposite of what we've recently found. Given that the descriptions showing in the SERPs have actually changed from what they previously were, perhaps this is a good indication that Google is currently testing out some new updates or algorithims in this area.

As for Yahoo showing pages that are more than 2 years out of date... is it possible there are some issues to do with the Yahoo/Bing affair that are causing this? I think we'll have to do some more investigation on this.