Recently Google advised websites that it would take HTTPS into consideration when displaying its search engine results page. The direct indication from Google can be summarized as follows:
If an SSL version of a web page exists, Google will show that page in the index.
That was it, a very simple concept. But we wondered, what kind of impact would an HTTPS version have on the actual ranking within a SERP? So we did some testing to find out. From our early returns, we have seen some indications that HTTPS does have a favorable impact on SERP's. But due to the constant changes on SERP's, it is hard to identify exactly the impact. And as is the case with other ranking factors, its almost impossible to quantify.
Our conclusion from this study is as follows: get HTTPS for your website! It may not have a major impact on your search rankings. But Google recommends it. And whatever Google recommends, we recommend. After all, you are creating a more secure experience for your users.