The official Pokémon Global Link website was expected to launch on September 18th, 2010 to coincide with the release of Pokémon Black and White but due to excessive traffic, the site has been closed for approximately 10 day for maintenance to deal with stability issues. Unaffected by this issue are the Wi-Fi random matches (Wi-Fiランダムマッチ) and Game Sync (ゲームシンク) options.

The following are a list of features that are affected by the downtime but normal service will return once the site issues are addressed:

• Pokémon Dream World - Allows players to upload their Pokémon to the website, Grow berries and decorate their house.
• Game Friends List (ゲームフレンドリスト)
• Pokémon Popularity Contest (ポケモン人気投票)
• Pokémon Pia (ポケモンぴあ) - Enter codes from the magazine to unlock starter Pokémon.

Source: http://www.pokemon.co.jp/info/2010/09/at100918_01.html

Wow, it's good that the Global Link site has been popular, but it's kind of scary that it's down already. Maybe the staff underestimated just how popular it would be. Hopefully they get this issue sorted out quickly. I just got both Pokemon White and the Pokemon Pia magazine today, and I was looking forward to seeing which of the Kanto starters I would get!

It shouldn't affect you other than having to wait until its back up again. You'd think they would have expected that having 1.5 million pre-orders would cause their servers to get hit hard. Hopefully they'll be able to setup the servers to handle the number of users. At least now they'll be a bit more prepared for the worldwide launch of the games.