There are a numerous rumours going on regarding this promo so we won’t find the exact details till tomorrow. According to macrumors.com:

Apple is expected to launch its Back to School promotion tomorrow, and on the eve of its launch, we’ve learned that Apple is indeed going to be making it their biggest ever.

According to our sources, Apple will be offering a free 8GB iPod Touch ($299) to college students who buy a qualifying Mac (MacBook, MacBook Pro, MacBook Air, iMac, Mac Pro). Alternatively, students may choose to get an 8GB iPod Nano ($199). The promotion will run from June 3 to September 15th, 2008.

Details of the Back to School promotion, including eligibility should be officially announced tomorrow.