I wrote a plugin for WordPress which requires regular updates.
Is it possible to notify user of new version being available (some of the other plugins have some kind of this option – when new version is available user can see it in his admin panel and update – everything using some built-in WP functions…)
There is a library for you. 🙂
I just released this plugin yesterday that does what you want: WP Updates Notifier
You can get your users to use this to be notified or take the plugin and bundle it into your plugin and modify to only notify about your plugin.