Google launched the +1 button, even before people knew about Google+, the social network. It was a way to tell Google that you felt a particular piece of content or search result was one of quality, and deserved to rank well in Google’s search engine. Now, Google’s Matt Cutts has admitted that it’s not really a great quality signal.

Cutts participated in a keynote discussion at SMX Advanced in Seattle, where he was asked about Google+ and SEO. According to a liveblogged account of the conversation from SMX sister site Search Engine Land, Cutts said, “When we look at +1, we’ve found it’s not necessarily the best quality signal right now.”

It’s unclear whether he meant this is the case versus other social signals (like Facebook likes) or whether social signals in general aren’t the best indicators of quality. It could be both in reality. I made the case here, why social is not always a great indicator of relevancy, but there’s also the matter of how frequently people are actually clicking on +1’s, compared to Facebook likes, tweets, and other social buttons.

During the keynote, SMX’s Danny Sullivan asked Cutts if you have to be on Google+ to rank well in Google. According to the liveblog, his response was, “No!!!! It’s still early days on how valuable the Google+ data will be.”

For Google’s sake, I hope Google+ and +1s do evolve into better quality signals, because Google sure seems to be placing a pretty good amount of eggs in the Google+ basket, tying it into its various products, and making it Google’s “social spine”.

Clearly Google and Bing both consider social to be a pretty important factor in search, as evidenced by this year’s launches of Search Plus Your World, and Bing’s new social redesign.

In a Google help center article, it says, “+1’s can help improve Google Search too, since you can see which pages your social connections have +1’d right beneath search results and ads.”

Google says:

+1 gets conversations going. Click the +1 button to give something your public stamp of approval. Then, if you want to share right away, add a comment and send it to the right circles on Google+.

The next time your friends and contacts search on Google, they could see your +1. You’ll help them find the best stuff on the web – and you might just start up another conversation!

I guess +1s are not the new PageRank just yet. Clearly, your Google+ presence (namely, your Google Profile) still has some important effects on search visibility though.

Word is (at SMX) that Pinterest is a pretty strong social signal to search engines these days. Bing’s Duane Forrester appears to concur.