An interview with actor Harry Lloyd, cast as Viserys Targaryen, in the Gay Times mentions his enthusiasm for the project and the role. The relevant paragraphs can be found on the third page  of the feature, transcribed below:

“Refreshingly down to Earth for a 26-year-old in his position, he refers to himself as ‘a worrier’. Which makes it all the more gratifying to see him talk about his current other project, a pilot for a new HBO fantasy series, Game of Thrones, based on a range of books. He likens it to a less-magical Lord of the Rings (‘big battles, political and quite dark’) and gleefully describes his role as ‘a brilliant fucking character, a really nice nasty part’.

“It’s something he returns to throughout our interview, each time becoming so animated that I actually want to put in a call to the television network and demand they commission a full series as it clearly means that much to him.”

(Hat tip to Winter is Coming commentator, the rabbit, for digging this one up first!)