Before games are shipped, they are rigorously checked for bugs, flaws, and other unsightly imperfections. When a game has been certified as passing quality control, it's "gone gold." The game is then shipped to manufacture. This usually happens a good length of time before the game's actual release date to ensure that there's enough time to print sufficient stock, to weed out defective products, and to get a cheaper rate on printing/manufacturing costs. But in the case of the most hotly anticipated titles, the final bugfixing and fine-tuning can take a very long time, and things are often tested, fixed, and re-tested up until the very last minute before the game code has to be sent to disc replication and packaging companies.

You may remember hearing how Rare had to send Perfect Dark Zero to manufacture just days before the X360 launch - taking a huge gamble in that the game hadn't passed all of its quality control checks yet. But they needed 700,000 copies on launch date, and to make sure they had that stock on hand, they had to send the game to manufacture at a specific time. Fortunately, the game passed QC days after it went to the replicators, but if it hadn't, Rare would have needed to re-program and re-manufacture the game - an expensive process that would have delayed the game's release past the X360's launch date.

Could something similar have happened to Nintendo with SSBB in Japan? Maybe they found a nasty bug in the game and had to re-do a manufacturing run with fixed code on short notice. Or perhaps they were fine-tuning things up until the very last minute, so much so that they knew they'd have to push the game's release back a week to have any copies out on the market at all? This could explain the US SSBB's delay, as well - better to have time to make sure there's plenty of stock on hand than to have the game released earlier, but risk leaving fans embittered from a shortage...