On the first day that the popular iPhone was available at Verizon Wireless stores, an iPhone is displayed in Beachwood, Ohio, holds up an iPhone on Thursday, Feb. 10, 2011. (AP Photo/Amy Sancetta) (Amy Sancetta/AP)

Some users of the MyWi program, which lets iPhone users tap into their phone’s Internet connection for other devices, are reporting they have received text messages and e-mails from AT&T indicating that the company knows what they’re doing and will automatically enroll users in a tethering plan if the notifications are ignored.

TiPb and modmyi.com were the first to post about the notifications. TiPb hazards the guess that AT&T is finding MyWi users by looking at who is using the Hotspot feature on an iOS prior to Apple’s latest, 4.3, which has a built-in hotspot feature.

The text messages read, “AT&T Free Msg: Did you know tethering your Smartphone to a computer requires a tethering plan? Pls call 888-860-6789 for details or visit att.com/dataplans.”

Both blogs have posted the e-mail AT&T’s been sending out:

Dear [Customer],

We’ve noticed your service plan may need updating.
Many AT&T customers use their smartphones as a broadband connection for other devices, like laptops, netbooks or other smartphones– a practice commonly known as tethering. Tethering can be an efficient way for our customers to enjoy the benefits of AT&T’s mobile broadband network and use more than one device to stay in touch with important people and information. To take advantage of this feature, we require that in addition to a data plan, you also have a tethering plan.
Our records show that you use this capability, but are not subscribed to our tethering plan.
If you would like to continue tethering, please log into your account online at Cell Phones and Cell Phone Plans – Wireless from AT&T, or call us at 1-888-860-6789 Monday – Friday, 7 a.m. – 9 p.m. CST or Saturday, 8 a.m. – 7 p.m. CST, by March 27, 2011 to sign up for DataPro 4GB for Smartphone Tethering.
Here are details on the plan:
DataPro 4GB for Smartphone Tethering
• $45 per month (this gives you 4GB in total, combining both your smartphone data plan for $25 and the tethering feature, $20)
• $10 per each additional GB thereafter, added automatically as needed
• Mobile Hotspot capabilities are included for compatible Smartphones
If we don’t hear from you, we’ll plan to automatically enroll you into DataPro 4GB afterMarch 27, 2011. The new plan – whether you sign up on your own or we automatically enroll you – will replace your current smartphone data plan, including if you are on an unlimited data plan.
If you discontinue tethering, no changes to your current plan will be required.
It’s easy to track your usage throughout the month so there are no bill surprises. For example, we send you free text messages when you reach 65, 90, and 100 percent of your plan’s threshold. If you would like to monitor your account more closely, go towww.att.com/dataplans to learn about other ways to track your data usage.
As a reminder, our smartphone data plans also include unlimited usage of Wi-Fi at no additional charge. AT&T smartphone customers can use Wi-Fi at home or on-the-go at any one of our more than 23,000 U.S. hotspots already included in your data plan.
Thank you for bringing your account up to date. We appreciate the opportunity to continue to serve your mobile broadband needs.

Any readers who’ve tethered the AT&T iPhone had similar messages this morning?

Related stories:

AT&T confirms hotspot feature

Apple iOS 4.3 has built-in personal hotspot feature

$20 a month for Verizon iPhone hotspot