To make the image show up in your SERPs, here is what you do:
1. If you don’t already have one, go to the Google+ home page (plus.google.com), create a Google+ account.
2. In your Google+ account, Edit Profile, About, fill in the “Contributor to” sections.
Label: Whatever you want, for your eyes only (I think)
3, Edit “Other Profiles”, fill in with
Label: Whatever you want, for your eyes only
URL: http://www.yourdomain.tld/author/first-last/ (change to yours)
4. In Google+ profile, click the +1 header nav and enable “Show this tab on your profile”
(if the tab isn’t there, you must +1 at least one web page and the box will appear)
5. In Google+ profile, copy the URL up to the last number, like this: https://plus.google.com/106520462790997712160
6. On your blog, edit Your Profile and add this to the Biographical Info:
Connect with Dave on <a href="https://plus.google.com/106520462790997712160?rel=author">Google+</a>
(use your name and your unique number)
Alternately, you can have a link to your author page. If so, it must contain the rel=”author” tag, like this:
Written by <a rel="author" href="http://www.yourdomain.tld/author/dave-koopman/">Dave Koopman</a>
If you do this, you must also include a link to your Google+ profile with rel=”me” on your author page, like this:
<a rel="me" href="https://plus.google.com/106520462790997712160"> <img src="//www.google.com/images/icons/ui/gprofile_button-16.png"></a>
7. Go to https://plus.google.com/authorship and fill in your email and click signup. It’ll send an email you have to verify.
8. The results will not be instant. Go to http://www.google.com/webmasters/tools/richsnippets and enter a URL of an article you’ve written. Does it show your picture?
9. Wait indefinitely and hope that Google will pick it up and start showing your picture in their SERPs. I’ll update this post when they start showing mine and let you know how long it took.
[UPDATE]Seeing several articles say it takes months and there is no telling how long it’ll take. All you can do it set up correctly, keep adding quality content, and wait.[/UPDATE]
If you’re using WordPress, you can simplify some of the steps on your end by using the AuthorSure plugin. You still have to do all the Google+ profiling editing steps manually.