High rankings in Google search results are coveted by nearly all webmasters, but Google is constantly making changes to keep them on their toes. Actually, Google is said to make roughly one change per day.

One recent change in particular, however, has gotten some webmasters riled up. It's being referred to as "Mayday," and some claim it is costing them money.

Do you think the update has affected your revnue? Comment here.

Ex-Googler Vanessa Fox, who spoke on a panel with current Googler Matt Cutts at Google I/O last week, quotes Cutts as saying, "this is an algorithmic change in Google, looking for higher quality sites to surface for long tail queries. It went through vigorous testing and isn’t going to be rolled back."

She also says Google told her that it was a rankings change, as opposed to a crawling/indexing change. This, she says, "seems to imply that sites getting less traffic still have their pages indexed, but some of those pages are no longer ranking as highly as before."

"This change seems to have primarily impacted very large sites with 'item' pages that don't have many individual links into them, might be several clicks from the home page, and may not have substantial unique and value-added content on them," says Fox. "For instance, ecommerce sites often have this structure. The individual product pages are unlikely to attract external links and the majority of the content may be imported from a manufacturer database. Of course, as with any change that results in a traffic hit for some sites, other sites experience the opposite."

She has more to say about it at Search Engine Land, offering some of her own speculation. One reader accuses the change of delivering "a real blow" to his revenue.

This is not the first we've heard about "Mayday". There's been discussion about it around the SEO community all month, but this is the first we've seen it really addressed by Google.

Most savvy webmasters have learned by now that they can't rely on Google rankings alone to drive traffic. This is why social media opportunities presented by networks like Facebook and Twitter have become so attractive. The way people search and obtain information is becoming more and more diversified, not only spread out around different applications (largely due to increased mobile usage), but also within search engines themselves.

For example, Google recently rolled out its big SERP redesign, which gives users a great deal more options for filtering their results (or at least puts these options in the spotlight). The importance of ranking in a completely natural, organic search has become greatly diluted over time. Don't get me wrong, it's still nice, but it's getting harder to rely on as well as less critical for discovery.

Stay tuned to WebProNews for our exclusive interviews with both Cutts and Fox from Google I/O, in which they talk with our own Abby Johnson about a variety of search-related topics. They should be posted soon.

Do you think your rankings have been affected by the "Mayday" update? Let us know.