AT&T has announced new smartphone data plans, outlined below and effective January 22. This is the first significant update to AT&T's smartphone data plans in a year and a half, aside from AT&T's inclusion of an additional 2 GB of data per month for tethering customers. We've provided some comparison with the old plans so you can get some idea of what you're getting for your money under AT&T's new scheme.

New plans:

• DataPlus 300 MB: $20 for 300MB -- extra 300 MB costs $20
• DataPro 3 GB: $30 for 3 GB -- $10 per additional GB
• DataPro 5 GB: $50 for 5 GB, with mobile hotspot / tethering -- $10 per additional GB

Old plans:

• DataPlus: 200 MB for $15 -- extra 200 MB costs $15
• DataPro: 2 GB $25 -- $10 per additional GB
• Tethering: Additional $20/month for DataPro customers and adds an additional 2 GB of data

In summary, overall tier pricing has risen by $5 per month across the board, but the data plans are also more generous by 50 MB on the low end and 1 GB on the middle and high tiers.

AT&T also has two new tablet data plans for the iPad:

• $30 for 3 GB
• $50 for 5 GB

The existing $14.99 for 250 MB plan remains available. These are still month-to-month, contract-free plans available to owners of the iPad Wi-Fi + 3G models.

Existing customers can stick with their current plans if they prefer, but new AT&T customers will be limited to the new options after January 22.