you can now play games on the service from overseas -- mostly. While the company "has data centers throughout the world in various stages of tests," there no guarantee that logging in to the US servers from overseas will provide you with a solid experience. Basically, if you want to play OnLive while abroad, "give it a try," and hope it works.
That said, the company is aiming to set up sites all over the world, with Germany and Belgium-specific servers heading into beta later this year. Meanwhile, if you want to play games while too far away from the servers that are currently running, you'll have to play games the old-fashioned way: With disc-based media and powerful computing and graphics processors built into a slim case with a large LCD screen. That's right, just like the old-timers used to do it!