Not all plugins are created equal. The most widely used plugins will work with the most versions of WordPress and especially with the most recent version of WP.
When you pick up a new plugin from WordPress, check the FYI box at the top right of the plugin page.
Note the version of WordPress that is required for your plugin to work properly, if at all. Also, it may be important to note the highest version of WP that is compatible with the plugin.
The Plugin FYI Box also gives links to the author’s homepage and the plugin’s homepage so that you can find out a lot more about the plugin.