From their site, "Can I listen to Pandora outside of the United States?
Unfortunately, no: we can only stream Pandora to listeners within the United States.
Delivery of Pandora is based on proper licensing from the content rights holders-- and we have always believed strongly in honoring the guidelines as determined by the artists, labels and publishers. In the U.S. there is a federal statute called the Digital Millennium Copyright Act (DMCA) that provides this license for all the music you hear on Pandora. At this time, there is no equivalent license outside the U.S.
If you visit the Pandora Radio - Listen to Free Internet Radio, Find New Music homepage and you see that your access has been restricted, you may enter your email address to be notified if and when Pandora becomes available legally in your country.
In all honesty, we don't have the resources to pursue music-streaming licensing arrangements in many countries in the immediate future, but we do have the ultimate goal of being able to offer our service globally. We greatly appreciate your understanding and support."