Here comes a plugin that some of you have awaited for a while!
It's a plugin which allows you to backup the whole prefix of an application installed in PlayOnLinux, the version of Wine used with it (it's defined in "PlayOnLinux -> Tools -> Manage Wine versions"), and the launcher of that application.
It creates a .pol archive that you can reinstall when and where you want via "Install -> Install a .pol package or an unsupported application" in PlayOnLinux.