Some vendors have begun special trade-in promotions in the wake of yesterday's iPhone 4S announcement. Chief among these is eBay, which has launched an Instant Sale promotion that ends at 11:59PM Pacific time on Wednesday. The auction site is offering up to $357.50 for a 32GB AT&T iPhone 4, or $318.50 for an equivalent Verizon model. 16GB capacities can fetch as much as $325.50 or $297.75, respectively.
