Buy an iPhone 3GS in the last month or so? You might not be totally boned. [Update: Confirmed]

Update: We’ve just confirmed this with AT&T.

You needed a phone. Just about everyone with an Internet connection was telling you that a new iPhone was coming in June — but what do they know? You went ahead and bought an iPhone 3GS.

June 7th rolls along, and Steve takes the stage to proudly proclaim that the iPhone 4 is the best thing ever made in the history of ever. They might not say it, but you hear it in the undertones: Your 3GS is no longer magical. Plus, it’s cheaper now! Well, shoot.

Don’t panic! It looks like AT&T might be cutting recent 3GS purchasers some slack.

According to a memo acquired by ModMyi, anyone who bought an iPhone 3GS between May 7th and June 7th of 2010 can return the 3GS (at its original, pre-drop price) and snatch up an iPhone 4 in exchange, paying whatever price difference there may be.

If you instead opt to keep your 3GS and just want some cash back, that seems to be an option as well. If you bought the 3GS between May 7th and May 14th, you’ve got until June 14th to ask for some monies; if you bought it any time between May 14th and June 7th, you’ve got 30 days from the date of purchase. 16GB 3GS late-adopters will get 50 bucks back, while 32GB 3GS late-adopters will get $100.

The text of the memo:

This one-time Customer Price Protection will allow customers who purchased iPhone 3GS 16GB/32GB through a Local Dealer from May 7, 2010 until June 7, 2010 to receive a bill credit for the difference in the Manufacturer’s Suggested Retail Price in May 2010 and the new Manufacturer’s Suggested Retail Price plus sales tax. This special one-time credit from AT&T will be provided to customers of Dealer regardless of what price the customer actually paid for their iPhone.

* Customers who purchased iPhone 3GS May 7th through May 14th will have until June 14th to visit the original location of purchase and receive this one-time bill credit
* Customers who purchased after May 14th will have 30 days to complete their price protection transaction by returning to the original location of purchase
* The Price Protection Credit applied to the customer’s account will equal:

* $50 for the 3GS 16GB
* $100 for the 3GS 32GB

Return/Exchange Policy:

A customer who purchased iPhone 3G/3GS through a Local Dealer from May 7, 2010 until June 7, 2010, who would like to exchange it for iPhone 4 and pay the price difference, will be able to do so.

Update: We’ve just confirmed this with AT&T. Switching from a 3GS to a 4 is a bit complicated; you’ll need to go to the original store you purchased it at, pre-order the iPhone 4, and then make the return/switch when you pick up your iPhone 4 on June 21st.