A warning about 'Like' buttons

WordPress "Like" button responses consist of links added to your posts by readers who have Gravatar profile pages. These links don't have the nofollow attribute. What's more, this feature is enabled on Wordpress.com blogs by default. To opt-out bloggers have to disable "Likes" via a dashboard setting, or when they edit posts.

Like button spam

If there are 90 or more "Likes" a random selection of 90 Gravatar profile links will exist inside the page even if some are not visible (the WP development team tinker with how many to show).
Only registered WP.com users who are logged-in can 'like' a post.

Google this...

Google lets you confine a search to a single domain with the "site:" operator. You can also specify an exact phrase by putting quotation marks around the text string. Try this:
http://www.google.com/search?q=site:wordpress.com/+"Be the first to like this post"
You can repeat the exercise with any of the quoted text strings in the table below. You'll find that the vast majority of posts get less than a handful of "Likes".

"Likes" count  (2011-08-27)Results count
Wordpress.com “Likes” — blogs in English:
"Be the first to like this post"284,000,000
"One blogger likes this post"5,360,000
"2 bloggers like this post"889,000
"3 bloggers like this post"292,000
"4 bloggers like this post"127,000
"5 bloggers like this post"74,300
Wordpress.com “Likes” — blogs in Swedish:
"Bli först att gilla denna post"5,830,000

There's no way the "Be the first" count can be blamed on unused blogs ("Hello World!"), because the English language count alone is more than 10 times the total number of Wordpress.com blogs. There are a wide range of different languages to choose from. More than 300,000 new posts are added each day, so by the time you read this the "Be the first" count could be even higher.

If you have the Firefox PageRank extension a little bit of investigation will reveal that the Wordpress.com blog posts which receive lots of "Likes" are mostly pages with a Google PageRank value that's above average. Is that purely a coincidence? Or are visitors disingenuously clicking "Like" buttons to suck Google-juice to their Gravatar profiles, which in turn have links to their own blogs? They may not realize that links in their profiles do have the "nofollow" attribute, or maybe they just don't care because all they want is more readers.

Some people will say that better quality posts tend to accumulate a higher PageRank and it's the quality that attracts the Likes. To support that argument they would have to demonstrate that the posts received lots of Likes before the PageRank score started to climb. I know for certain that one of my WP.com posts had reached PR4 at least eighteen months before I received the first "Like". At the WP.com developers' blog new posts can be expected to acquire a high PR very quickly. Consequently, they get inundated with Likes. Other top rated bloggers seldom get such an immediate response.

'Sleepers'

If a Wordpress.com user with a Gravatar profile is logged in when they visit another member's blog they can "Like" a post even if it doesn't have the button. The user's Admin bar will have the button:

The "Like" still gets recorded. These Likes will be 'sleepers' waiting for the day when you relent and decide to re-enable Likes. There have been complaints about it at the WordPress.com Forums:
http://en.forums.wordpress.com/topic/spam-through-the-like-button