Today I was reading a post by Ozh on common coding mistakes for WP plugins and I got to this section:
I’ve seen code comments mentioning stuff like “// we’re doing this for people using WP 2.5″. This one is more a personal choice, but I think maintaining compatibility with older versions is a terrible idea.
Terrible for you: fixing bugs and implementing new features is quite a task already, don’t add to the burden with more deprecated code.
Terrible for the users: it’s nice that your plugin is going to run fine on their obsolete, insecure and already hacked blog, but it really does not motivate them to upgrade, which is vital.
I know I’ve dropped backward compat with my plugins a long time ago, and always code for the latest release available. It makes life so much easier.
In light of the recent security problem, I will follow his advice. So, as of today, all my plugins will only be tested on the latest stable version of WordPress.