In another blow to the beleaguered major labels, already rendered effectively obsolete last week when Radiohead allowed fans to download new album In Rainbows directly from the band’s Web site, Madonna announced today she has struck a multimillion-dollar deal with Houston-based concert giant Live Nation that will, among other things, release her new material through Live Nation once she has fulfilled her existing contract with Warner Bros. (She owes the label, which has released all her albums since 1983’s Madonna, one studio and one greatest-hits album.) Although financial terms were not disclosed in today’s announcement, the Associated Press estimated the deal to be worth $120 million over ten years.

“For the first time in my career, the way that my music can reach my fans is unlimited,” Madonna, 49, said in a joint statement with Live Nation. “I’ve never wanted to think in a limited way and with this new partnership, the possibilities are endless.”

According to the Wall Street Journal, the deal gives Live Nation the exclusive rights to release three Madonna albums and promote her tours, while in exchange, the pop superstar will receive a $17.5 million advance, an undisclosed amount of Live Nation stock, and advance payments on the three albums between $50 and $60 million. In addition, Madonna will keep 90 percent of her touring revenue, while she and Live Nation will split any revenue derived from licensing the “Madonna brand” (fragrances, merchandise, etc.) down the middle.

“The deal carries significant risks for Live Nation,” the WSJ’s Ethan Smith reports. “People in the music industry estimate that at current recorded-music prices, the promoter would have to sell about 15 million copies of each of its three albums to make back its investment on that piece of the deal alone.”

Madonna’s latest studio album, 2005’s Grammy-winning Confessions on a Dancefloor, has sold eight million copies worldwide. Shares of Live Nation rose eight cents to $21.50 after today’s announcement. Madonna is the first artist in Live Nation’s new Artists Nation division, which CEO Michael Rapino said in the statement will “partner with musicians to manage their diverse rights and provide global distribution and marketing.”

Although Madonna is now technically an employee of a Houston company, today’s announcement came from Live Nation’s L.A. office, and don’t expect to see her around the Bayou City anytime soon. The Material Girl’s last Houston appearance was May 5, 1990, when her Blonde Ambition tour opened at the Summit. – Chris Gray