Same thing happened to me and I just got off the phone with Apple support - they are saying that this has happened to a lot of customers and since it is a "developing story" they can not provide a lot of details. They did say however that if you made it to the checkout process your ticket was in fact reserved and once they get things sorted out they will e-mail you at your Apple ID to allow you to actually purchase your ticket.
Ah, I had just been viewing it in the browser; but I do notice these things as I'm a bit of a fan of the fluid to mobile idea. https://www.promosity.com <- my startup - fluid to mobile throughout
Indeed Amaz-ing work here Philippe; I'm impressed. I don't understand all of this copyright negativity. Perhaps I'm just naive in these matters, but so what if Amazon shoots you a cease and desist - BONUS! How great would that be for a follow-up blog post?
I think it's a great idea and I have been using a service very similar to this for a little while now - http://cannon.fm/ . So, good news? This seems to be a market with an established set of users who want a solution to this problem. Keep up the good work!!