AT&T $25 for 3 months of 1GB data is live

The plan is not available, along with the $5 for 1 day of 250MB.

The $25 for 3 months of 1GB may not sound like much, but it's probably the cheapest way to have a backup data plan for occasional use as it's about $8.33 a month (if you need more than 200MB a month).