After months of rumours, “Facebook phones” offering instant posting to the popular social networking site were unveiled this week at the Mobile World Congress in Barcelona.

None of these new mobile phones has an official Facebook logo on the back. But even a casual test shows that the controls revolve around status updates, pokes, likes and other Facebook features.

The site’s founder, Mark Zuckerberg, has a vision of the entire globe becoming a network of Facebook friends. And these new mobile phones lead that way. It is already estimated that one-third of Facebook’s 600 million members post or read friends’ updates on phones.

Apple’s iPhone and Android phones have had Facebook apps for ages.

What is different on the new devices is the phone does not feel like a tool that helps you connect to Facebook — it seems to be a part of Facebook already.

On “Facebook phones” from HTC of Taiwan, for instance, when the user takes a photograph the Facebook button blinks. It is urging the user to post that picture to the website.

When the cellphone plays a song that the user enjoys, it is possible to tag it with an instant “like” and share that with friends. If a Facebook friend phones, their profile comes up on the screen.

HTC calls the variant with a keyboard the ChaCha and the one with a touchscreen the Salsa.

Zuckerberg had denied in recent months that he was planning a Facebook phone. In a sense that has proved true — it’s not one phone, it’s dozens.

On a video conference call to Mobile World, he said even more phones with profound Facebook integration are on the way.

Last week a little-known maker, INQ, launched two phones that are built around Facebook, offering direct access to the user’s Wall.

Postings from friends constantly stream into the INQ phones’ news page and invitations and other events go automatically into its calendar. Like the HTC products, the INQ devices run on Android.

A smartcard company, Gemalto, has brought a novel approach to Barcelona — integrating some of Facebook’s more basic functions into the SIM card instead of the phone itself. The advantage is that the user can then interact with Facebook using practically any mobile phone.

This can be major money saver, since the user does not have to buy a costly smartphone or subscribe to an expensive data pricing option to send and see status updates, give and receive pokes and invitations, all of which run as texts.

The short message service (SMS) technology does not handle photographs and videos, but this mode of Facebooking could have enormous appeal for budget-minded users. Gemalto’s Facebook for SIM service will not be free, but financed by subscriptions.