Is anonymous online commenting ethical?

Should anonymous commenting on blogs, forums, social networking sites and microblogging sites such as Twitter be allowed? Is it ethical?

I’m inclined to lean strongly towards the negative argument. I’d suggest that anonymous posting goes against the very fundamental principles behind social media and the importance of authenticity and transparency when operating in online communities. It’s therefore very interesting to see that there are new online tools and services popping up that encourage this very behaviour.

Two of the latest examples are as follows:
Tweet From Above
Tweet From Below

The company’s tagline is: “Anonymous Tweeting: For what has to be said, just not by you”

One of the services implies tweeting for ‘good’ and the other for ‘bad’.

I’ll be interested to see the sorts of tweets that get shared on both of these services. I’m particularly interested to know what sort of tweets make it to the ‘Tweet From Above’ service. If there’s something good to share – a fabulous CSR initiative by a company, something great that a colleague has helped you with, your love of Sunsilk shampoo – why not put your name to it and share it with the world?

I can understand the reason for not putting your name to posts that comes from ‘Tweet From Below’, but surely this is just another service that has the potential to flare up cyber-bullying!

Are there any valid reasons for commenting anonymously? The assumption would be that one would only do so if they have something to hide. Perhaps what they are posting is factually incorrect or perhaps they are simply gossip mongering. Whatever the case, I don’t agree with it.

I’d be keen to hear if anyone has any thoughts on when anonymous commenting would be permissible.