I read somewhere that it only affects Linux and Unix operating systems ....Although there may be some minor exceptions, I believe that is essentially true, if "Unix" is considered to include Unix-like operating systems such as the various versions of BSD.
To be sure it's clear, though, this refers to the OS of the web server used by the site, not to the OS used by the individual who is communicating with that server. The OS on an individual's computer makes no difference.
And my understanding is that the majority of the world's web servers run Linux, although many of them do not handle encrypted traffic, and many of those that do aren't using the versions of OpenSSL which have the vulnerability.
Also, yesterday Audiogon posted the following in the Hub section:
Audiogon.com is no longer vulnerable to the Heartbleed bug. All of our platform providers have taken steps to prevent exploitation of the Heartbleed vulnerability by updating OpenSSL. We have restarted all resources using OpenSSL. If you have not already, we recommend you change your password.Best regards,
-- Al