Probably. It's happened in the past. However, you realize you'd still have to buy the iPod touch; you get a rebate that you submit for the cost of the 8 GB iPod touch.
You should be able to call Apple and have them "return/rering" your computer purchase. For the rebate they have to be on the same receipt, so they'll return the computer, "charge" you for both, then you can sign up online for the rebate.