The team behind the Chrome web browser have proposed that the browser will make it much more obvious to the user when a site isn't using an SSL certificate (i.e. it hasn't got https:// at the beginning of the domain name). While just a suggestion at this stage, it is in line with the previous news that Google have already started increasing the ranking of sites that use an SSL certifcate versus those that don't.
Google's reasoning is that the only situation that you don't see errors (other than when the site has a valid SSL cert) is when a site has no certificate at all. This may induce a false sense of security where there is none.
Their suggested first step is that non-secure sites are marked "dubious" in Chrome. Coupled with the ranking improvement, it seems that planning to add a secure certificate to your website will become almost essential in the coming months.