There is an information from Google adsense Admin, that the web will be down start from Saturday April 11,2009
This is the information detail :
"Our engineers will be performing routine site maintenance this coming Saturday from 10am to 2pm PDT.
Although you won't be able to log in to your account between these hours, we'll continue to track your clicks, impressions and earnings as usual. In addition, ad serving and targeting won't be affected.
We've converted the maintenance start time for our international readers:
London - 6pm Saturday
Bucharest - 8pm Saturday
Kolkata - 10:30pm Saturday
Bandung - 12am Sunday
Sydney - 3am Sunday
Thanks for your patience. In the meantime, if you're curious about what goes on during these maintenance periods, check out this post from one of our AdSense engineers.
Posted by Arlene Lee - Inside AdSense Team