Can I transfer iTunes purchases to new iTunes account
It's obvious Apple has a build in procedure to block this kind of actions. Otherwise they would go bankrupt... (Haha :)) 

However there are some work-arounds:


eHow.com has dedicated a tutorial concerning this issue. I haven't tested it, but the intro states it will do what you've asked
another way to do so is to just use both account on your iTunes, iPhone, iPad,... I do it with my iPad as well (both US and Belgium account) and yes it's a hassle, but it does the trick. I can access the apps, music and more from both accounts.