ModMyi reports that it has received an alleged AT&T memo from a source that claims the carrier will only be taking pre-orders for the black iPhone 4 models. The white model will become available "later this summer. "

According to an image taken of the memo the iPhone 4 will be available in black only for pre-orders and launch day. This means that you will only be able to purchase an iPhone 3GS in 8GB and the black iPhone 4 in 16GB and 32GB.  The white version of the latter two models will be available sometime after launch date.

We don't have any information about whether these restrictions apply only to AT&T or how they will affect other retailers including Apple. We reached out to AT&T's Mark Siegel for comment and his response was that AT&T had "no comment." We tried to get a comment from Apple, but at press time we had not gotten a response from them yet.

We'll find out for sure tomorrow since Apple and other retailers will start taking pre-orders for the iPhone 4 tomorrow morning.

Updated 06/14/2010 at 5:07 PDT: According to Engadget (who received the same comment that we did from AT&T) and AppleInsider Soft Bank of Japan and Deutsche Telecom won't have any white iPhones for launch day either so it looks like the problem will be more widespread than expected.