SMS what? Facebook stole the show this week with the launch of its free Facebook Messenger app, available for iPhone and Android users.

The app has garnered impressive download numbers as consumers opted for its streamlined mobile access to Facebook messaging with group texting options.

The social network has now crowded the group messaging app scene, creating fair competition for services such as Google+ Huddle. Facebook Messenger has even led some to forecast future irrelevance of basic SMS text messaging as mobile multiple-person messaging apps grow in prevalence and popularity - group messaging has been identified as a top trend of 2011 on readwriteweb.com.

Facebook Messenger is a sleek and tappable version of the Facebook message inbox. It combines recent chats as well as e-mails and message threads. Unlike Google + Huddle, a message recipient will recieve both notifications and a text message.

Message previews in the Facebook app include the sender's profile picture, lines from the message and the people involved in each message (and the number of people if it's several individuals).

One feature the Facebook messenger doesn't offer in comparison to Google+ Huddle is the ability to name conversations and groups, such as the dining-focused "Gastronauts" example in Google's widespread Google+ Huddle demonstration video.

While Facebook Messenger and Google+ both involve group messaging, the Facebook app lets users send group messages to Facebook contacts and other contacts in their phone at the same time. As if the more then 750 million people signed up for Facebook wasn't already an advantage the app had against the young Google+, which now has more than 25 million users.

Also, with Facebook Messenger users can turn off or adjust alerts frequency for specific conversations (or all their messages) and see the locations of all the participants in a thread if those users are sharing that information.

While Google hasn't amped up features for Google+ Huddle yet to match Facebook's, Apple's iMessage is posed to offer Apple product owners similar messaging features.

Apple's new messaging service, iMessage, will be available to all users with the iOS 5 when the operating system upgrade is released this fall. According to Apple, unlimited text messages can be sent via Wi-Fi or 3G among iPads, iPod touches and iPhones. It'll automatically be activated when one goes to send a text.

iMessage will offer group texting with the ability to send photos and videos. It will also offer delivery receipts, a feature also available on Facebook Messenger. Apple users will also be able to switch devices while picking up a conversation at the point they left it last. When people are writing in iMessage, an ellipsis will appear to let the recipient know someone is responding.

Macworld.com.au reported uncovering a hidden video chat Facebook Messenger component that isn't functional yet, but it could be a signal of where Facebook is headed with its new app.

Facebook Messenger is powered by mobile group chat startup Beluga, which Facebook acquired earlier this year.

Twitter users have had mixed reviews about the app - many expressed excitement that Facebook has jumped on the group messaging bandwagon.

Adam Coomes (@adamcoomes) tweeted this week that "the new Facebook Messenger mobile app is slick. It's basically Beluga w/ Facebook integration. I'm loving it! Deleting Beluga & GroupMe."

Ji Lee (@PleaseEnjoy) wrote that she was "loving" the new messenger with its "awesome features: Group Chat + Locations."

The most popular Facebook Messenger tweet, however, was anonymous avatar @DeathStarPR (with more than 135,000 followers) playfully criticizing the messaging movement. "In our galaxy, instead of using Facebook Messenger we use a thing called Actually Talking to One Another. You should try it."

Privacy scare jolts Facebook users

Meanwhile, Facebook grabbed extra attention this week not solely because of its new messaging app.

This week people began reposting a message that Facebook was publishing all the phone numbers someone has in their phone. However techspot.com reported that the digits appearing in an individual's Facebook contact phone book is an accumulation of what people have added into their Facebook profiles. While users may sync their Facebook contacts with their phone contacts, the information won't be distributed unless it falls victim to a hacker.

Also this week, Hacker group Anonymous released a YouTube video vowing to "take down" Facebook on Nov. 5, spurring international news attention, but lacking concrete information about how real the threat is.

But the negative attention doesn't seem to have hacked away at the Facebook Messenger hype.