A recent report from PricewaterhouseCoopers titled "Global Entertainment and Media Outlook: 2006-2010" predicts the worldwide game market will see enormous growth, going from about $7 billion in 2005 to as much as $47 billion in 2010. That's almost seven times the current market value (here calculated for those who, like me, have reallocated brain cells previously used for algebra to trying to figure out Lost).
The bulk of this growth is not expected to come from the US, however. PwC predicts Asia Pacific will hold its leadership position over the next few years, with increased broadband access, computer literacy, and government promotion being the key factors driving sales in that region. The combined region of Europe, the Middle East, and Africa is expected to lead the globe in terms of growth.