If they do end up announcing new iPods on Sept 1, it probably won't go on sale until after Sept 7
The past two iPod touch generations have been released on the same day they were announced. Why would they change that?
http://store.apple.com/us/browse/campaigns/back_to_school
*Buy a qualifying Mac and iPod with Apple education pricing from May 25, 2010, through September 7, 2010, and receive an online rebate up to $199. 8GB iPod touch is second generation. Terms and conditions apply.
http://www.apple.com/promo/pdf/BackToSchool_TermsConditions_US_2010.pdf