More evidence of an upcoming 8GB iPhone 3GS model has appeared on Rogers Wireless’ website. Under the “iPhone Comparison” tab on Rogers’ iPhone 3GS mini-site, the company has posted a comparison chart for the iPhone 3G and 3GS which shows an 8GB option listed for both models. Curiously, the chart appears to be the only current reference to an 8GB iPhone 3GS on the site, which otherwise notes that the 3GS starts at $199 for…