Can a transaction be anonymous?
Not yet. I disagree with this. Transactions arn't mean to be anonymous. (vivou)
It's not currently possible to make a transaction anonymous as the list of transactions sent or received by an account is public.
[note Hugo] I would insist on the fact that blockchain is a public record of all transactions. Therefore all transactions are public, but the link between the account and the person behind it can be made hard to establish. We should discuss how to organize this article better. Maybe invite @tuxmain to the discussion, who understands well english and is very interested in this question. Also this part will change a lot with v2, so it will have to be updated with v2 [end note Hugo]
This functioning is necessary for the security of the currency, from a technical point of view. However, it's possible to make a transaction anonymous by a mixing technique (a technique utilised in the bitcoin field also).
As far as we know, ĞMixer is the first libre alternative in the world for monetary mixing.
ĞMixer applies the onion routing communication technology (originally developed for Tor) to the money: instead of passing the transaction through one unique mixing account, it sends the transaction to an account, which resends it to another, and so on until the destination account. Each mixing node only knows the account it receives the transaction from and the one it sends the transaction to.
The software that can do this "mixing" easily and in a secure way (the first secure money mixer in the world!) is being developed (more info here).
Meanwhile, you can open several accounts that won't create G1 currency (simple wallets), and use these accounts in an anonymous way, sharing no identity and no comments. Also make sure to receive and make payments on accounts that are also anonymous.