If you drop out to the old Windows Azure 90-day trial link right now, you'll still see the old offer available…

…but when you try to step through the sign-up process, it will tell you that the 90-day offer is no longer available.

However, if you navigate through from the primary Windows Azure site, you'll see that the Windows Azure trial offer has changed.

As of today, Microsoft has officially changed the offer, giving you 1 month or $200 worth of usage – whichever comes first.