You basically need to change 2 files to add the Google +1 button to the Pebble Blog.
First, add the Google +1 button javascript code at the end of your favorite template. This should be located somewhere around themes/your-theme/template.jsp
<script type="text/javascript" src="https://apis.google.com/js/plusone.js">
</script>
<script type="text/javascript">
(function() {
var po = document.createElement('script');
po.type = 'text/javascript'; po.async = true;
po.src = 'https://apis.google.com/js/plusone.js';
var s = document.getElementsByTagName('script')[0];
s.parentNode.insertBefore(po, s);
})();
</script>
Second, set the button tag within the entry Java server page. So it does appears right behind the title of each blog entry. You will find the file in WEB-INF/jsp/blogEntry.jsp
<h1>
<a href="${blogEntry.permalink}">${blogEntry.title}</a>
<g:plusone size="small" href="${blogEntry.localPermalink}"></g:plusone>
</h1>