While this is just speculation, I see no reason that Google doesn't open source their Android Market client software - after all, many other companies have good and solid paywalls that haven't been defeated by fully modifiable software - I can still buy things on Amazon using a modified copy of Firefox, with a patched Gecko engine, and I still have no access to the content until I pay.
Yet, why can't Google do the same? Is it because of the multiple Android Markets, one per nation? Are they afraid that someone's going to simply patch the part of the code that says to connect to, oh, the Belgian AM server to instead connect to the US AM server? Google runs AM, so why the hell don't they solve THAT issue by using IP-Geolocation? It's difficult to fake an IP address. Of course, Google will argue that people will go to different nations to get apps only available there.
In that case, take a hint from the Portal developers. "In the case that skipping ahead arguably takes more skill than solving the puzzle proper, we let the ninja solution stand." - that is, if someone would fly overseas just to get apps from the US Android Market, just let them do it - they already spend $1000 just to get here.