right, here's the info I've found out...
Tickets are only available to people who have 'won' them. To win them, you have to either send them a text message and hope they pick you, the same as they did for the Hyde Park gig. Or you can send them a postcard and hope they pick you, which actually works out a lot cheaper. I'm gonna send about 20 postcards and hope for the best!
Here's the site for more info on the tickets...
http://www.live8live.com/tickets/index.shtml