The recent sold-out Pitbull concert, the Java Jazz festivals and the upcoming All Time Low concert, among others, are trends indicating these things:
a smarter consumer. I remember not too long ago, pre-sale tickets didn't sell so well, online or offline; which might indicate consumers who can't decide on watching the concert or not until the last minute, or, lack of finances. Now presale drives a large number of ticket sales acts as a domino effect for more ticket sales and PR for the concert itself - the consumer knows what they want and can manage their finances better (whether or not it is actually money from parents.
wider acceptance of the internet as a medium for commerce. Also not too long ago, people were still reluctant to pay for stuff online. In the case of the Java Jazz Festivals, they were forced to buy online anyway if they wanted the early bird tickets; eventually, online purchase has become a way for many consumers to ensure they get their tickets, as opposed to standing in line all day at the ticket box.
the internet, via social networks, becoming the dominant communication tool, either for asking feedback on proposed artists, notification of promotions, and announcements of upcoming concerts. Java Musikindo and Java Festival Productions have skillfully used Twitter, Facebook and other means to promote their shows and obtain feedback from the crowd.
I think it's a good sign of things to come.