As of yesterday ESPN has stopped sending out text alerts to Sprint, Nextel, Boost, and Virgin Mobile users. I've been checking around and still haven't found a definitive reason. According to the Sprint Community forums people have been calling both parties and each are blaming the other. But apparently Sprint has raised its rates to send text messages and ESPN is refusing to pay it. There is an article about the increase here...
Telescope Inc. - iTV & Mobile Marketing
I just signed up for another site so I can get MLB score updates. This site also has news and other alerts available...
4INFO Home - Free Mobile Alerts and SMS Search and SMS Alerts