My understanding is that Yes, it is free to download and use in a business environment.
Things to note however:
1. Unless Adobe have changed the Ts&Cs, you cannot host the plugin, so users will need to go to the Adobe website to download the plugin.
2. Whilst Adobe are keeping the plugin available indefinitly, they are not longer developing it. You don't need the plugin with FireFox, but if most of your users are using Internet Explorer then be aware that there isn't currently any migration path. Depending on what you want to use it for you might find that Flash would be worth considering.
