[Update: At 10:28, I was told that the site is up and running again... www.xbox.com/rewards.]

Ah, word from the marketing team about the Achievements Reward Challenge.  They're telling us that because of the tremendous response from you all, it temporarily overloaded their servers.   Before apologizing, let me say THANK YOU for your patience as we work through the issues, and thanks for the awesome response to getting signed up.  Sorry that it's been a headache.  Tony, Chris, Sara, Larry, Trixie, and I have all gotten several emails in the past 24 hours, and we've read all your comments. 

As much as this is a "marketing opportunity," it has only come to fruition because a few passionate employees are determined to give back to our community as much as we can, so they've pushed and plodded and planned.  I know I bring it up a lot, but the thing that keeps us all going is that we're all gamers too, and we love having such an active, vocal community. 

So anyway, here's what they're telling us:

Thank you for the incredible response to Xbox Rewards. The gaming community’s interest has temporarily overloaded our servers and caused delays for those trying to register.

To help ensure everyone who wants to participate has the opportunity, the Old Spice Experience Challenge will be extended by three days. Now you have until April 15th 2007 to increase your Gamerscore by 1,500. 
 
As a bonus, we are adding more rewards for this challenge, which means more gamers who successfully complete the challenge will get rewarded.
 
Our development team is hard at work to fix the problem. We expect the web site will be ready in 48 hours, please be patient and check back periodically.

We'll tell you more the minute we get more info.