AT&T will be making some changes to its existing data plans on June 7th, the same date it’s rumored Apple will announce the next iPhone. Unlimited data will be going away, and in its place, AT&T will finally offer tethering.

Here’s what you’re looking at for plans:
– DataPlus. Provides 200 megabytes (MB) of data – for example, enough to send/receive 1,000 emails (no attachments), plus send/receive 150 emails with attachments, plus view 400 Web pages, plus post 50 photos on social media sites, plus watch 20 minutes of streaming video – for just $15 per month.** This plan, which can save customers up to 50 percent off their wireless data charges, is designed for people who primarily like to surf the web, send email and use social networking apps. If customers exceed 200 MB in a monthly billing cycle, they will receive an additional 200 MB of data usage for $15 for use in the cycle. Currently, 65 percent of AT&T smartphone customers use less than 200 MB of data per month on average.

– DataPro. Provides 2 gigabytes (GB) of data – for example, enough to send/receive 10,000 emails (no attachments), plus send/receive 1,500 emails with attachments, plus view 4,000 Web pages, plus post 500 photos to social media sites, plus watch 200 minutes of streaming video – for $25 per month.** Should a customer exceed 2 GB during a billing cycle, they will receive an additional 1 GB of data for $10 for use in the cycle. Currently, 98 percent of AT&T smartphone customers use less than 2 GB of data a month on average.

– Tethering. Smartphone customers – including iPhone customers – who choose the DataPro plan have the option to add tethering for an additional $20 per month. Tethering lets customers use their tethering-enabled smartphones as a modem to provide a broadband connection for laptop computers, netbooks or other computing devices. Tethering for iPhones will be available when Apple releases iPhone OS 4 this summer.

The big thing you might notice in there is that 98 percent of AT&T smartphone customers use less than that 2GB limit, according to AT&T anyway. All in all, the plans seem pretty flexible, but I have a feeling the people who go with tethering will be paying some pretty exorbitant fees for the service. It might be difficult to hit 2GBs of traffic on your smartphone. It’s another matter entirely on your laptop.