Google has warned that in the next version of Chrome (due in January), users will receive a warning on any non https website that has password logins.
You can identify sites that already pass this test as they will have a green padlock on the address bar (as this site should), and the address will start https:// rather than http://. Any site that users log into that does not currently pass this test will need an SSL certificate installed before January if they want to avoid this warning being presented to users.
Eventually, Google plans to warn users against ALL websites without an SSL certificate (although no date has been announced for this). They are already using the presence of an SSL certificate as a ranking factor in their search results.