The WSJ has some behind-the-scenes detail (r.r) on the Live Nation decision::

The situation threatens to create an acrimonious war over who will sell tickets for a big portion of the U.S. live-entertainment industry. A memo circulated within IAC/InterActiveCorp’s Ticketmaster, which controls the ticket inventory to nearly all major concert and sporting events in the U.S., said the ticketing company no longer expects to renew its agreements to sell seats for events at buildings owned by Live Nation, its largest client. Events at venues owned by Live Nation and its House of Blues subsidiary generated 17% of Ticketmaster’s roughly $1 billion revenue last year.

Talks between the two sides have grown acrimonious during the past year and a half, according to people close to the situation. Live Nation Chief Executive Michael Rapino has threatened to start his own ticketing operation rather than renew with Ticketmaster.

The story also mentions another revenue stream at stake:

Beyond the financial stakes, though, is another crucial asset: Control of the relationship with fans. One of the most valuable assets Ticketmaster has long controlled is detailed data on music fans’ spending habits, along with direct-email access to buyers.