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.
(emphasis mine)
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.
Each time I write a new plugin, I only ever test it with the latest version of WordPress. What I do do, however, is make a concious effort not to break compatibility with the previous major version (so 2.7 currently) whenever I update a plugin. This is only really in consideration for people who might be a little slow updating.
I think I might be a little more strict from now on, following Ozh’advice and your decision. Any pieces of code in my plugins which are explictly there to provide backwards compatibility will be removed (not that there are that many IIRC). I think users need all the incentives they need to keep updated at the moment.