March Madness is typically all about filling out brackets; entering a pool, and skipping out on work to watch a game or two. This year, it appears carriers and media companies want to make it about mobile content, too. In counting up the number of high-quality options that are being offered for free in connection with March Madness, it’s not hard to come to the conclusion that the industry is trying to turn the high-profile and addicting event into a mass introduction to mobile content. Who knows, it’s probably worth a shot. Once the tournament ends, they might just find users returning. But if not careful, users may end up feeling burned by high data charges or unsatisfactory experiences.

The NCAA basketball tournament kicks off this weekend when teams are selected. Here’s some of the announcements we’ve noticed so far, and there’s probably many more we are missing:

-- AT&T (NYSE: T) is launching a free NCAA March Madness portal on its MediaNet deck, which will feature tournament news stories, score updates, polls and NCAA basketball trivia and video highlights from every game. There’s also a bracket challenge that will allow users to compete against each other for a chance to win $10,000. Prizes will also be awarded to entrants who correctly predict the winners of men’s tournament games. In addition, AT&T customers and other wireless subscribers will be able to text to vote for the 2008 Naismith Trophy, presented by AT&T, which names the annual men’s and women’s college basketball players of the year. Release.

-- Sports Illustrated Digital is launching a fee mobile application next week called MySI Mobile just in time for March Madness. The application lets fans track scores, schedules, standings, view Sports Illustrated photos, read news and set alerts for upcoming games. The application, built by Action Engine, is subsidized by advertising.

--—go2 Media said it has developed a WAP site exclusively for the Men’s NCAA Basketball Tournament. Available now, the site at http://marchmayhem.go2.com has game and telecast schedules as well game results updated every minute. It will also have original content written by go2 correspondents. Text message alerts are also available for free. Release.

-- More: Mobile users can go to ESPN.mobi to Play ESPN’s (NYSE: DIS) Tournament Challenge, and fill out a bracket starting March 16; CBSSports.com is launching significant digital campaigns. It’s tournament brackets will be available online and on CBS (NYSE: CBS) Sports Mobile.