I just upgraded from iTunes 4 to iTunes 5 and, wouldn't you know it, Apple changed the global navigation system. Instead of placing the link to the "global gaeway" in the upper left corner of the music store, the link has been demoted to the very bottom of the page, as shown here:

iTunes 4 (Germany)

iTunes 5 (US)

Apple no doubt wanted to free up that valuable real estate at the top of the page to promote more products. And, because users cannot purchase songs across borders, the global gateway is of somewhat less importance. The way things work now, if you want to purchase songs from different country stores, you need to set up separate accounts. I'm sure this is completely driven by license limitations.