http://phantasystaruniverse.com/news_beta.phpI got an email about it a few days ago, and they've just recently changed the launch. It was going to be tommorrow, but they say that it should be "very soon".
All XBL Gold Members will be able to download the beta and play, but download will only be available during the day of the release, and the day after. Watch that page for the new release date. I'll try to update this when they release it.
UPDATE: The game will be downloadable this weekend, presumably this Saturday and Sunday. After this weekend it will not be downloadable. I will repeat this is only playable for gold members.
UPDATE 2: The beta is out. Check the Xbox Live Marketplace under games. Newly released downloads under the name "phantasy star universe" for all XBL Gold members in Europe, America, and Japan.