When ever it comes to Google making announcements that influence their algorithm / ranking factors, it's usually dropped like a bomb and search engine experts / web designers are expected to pull a rabbit out of a hat and make big changes in next to no time.
In a strange turn of events, this time Google is actually giving us a heads up about a big change to do with mobile-friendly websites. Come April 21, 2015 Google will be expanding their concentration on mobile-friendliness as a ranking signal. What does that mean? If you don't have a mobile-friendly website and your competitor does, your competitor is going to rank higher than you (assuming you have similar authorities, etc, etc.).
This is a big deal for website owners who's websites are not mobile friendly because changing your website to be responsive is not a simple matter at all. If you don't have the time or resources to do this, it might be a good idea to get someone to at least install a script that will switch between a desktop and mobile version of your website and put a simple mobile version in place as a placeholder.
How do you know if your website is mobile-friendly in Google's eyes? Fortunately they've created a tool that will allow you to check:
Useful resources:
- Guide to mobile-friendly websites
- Mobile usability report (Google Webmaster Tools users)