All public AL topics can now be shared through facebook or twitter. We shall be adding and publicizing our own facebook and twitter accounts soon, too. Until then, feel free to Like, Share and Tweet away.
Facebook does not really distinguish between the different replies, so only topics can be liked and shared. You will find the sharing buttons at the top of the topic:
We are using facebook's javascript API, so only browsers with javascript enabled will get to see the buttons. Browsers with content viewing restrictions possibly won't allow the buttons.