According to numbers compiled by online advertiser Chitika, only 55 percent of iPod touch users have paid the fee to upgrade their devices to OS 3.0 or higher. Nearly 95 percent of iPhone users have made the free upgrade. These numbers were based on the sampling of traffic across the Chitika advertising network.
Chitiaka attributes this, aside from the obvious price difference, to OS 3.X having little to offer the typical iPod touch user. "Push notifications? MMS? Tethering? Essentially useless on a device that relies on WiFi for a connection. iPod touch users are essentially asked to pay for copy/paste, in-app purchases, and the ability to buy a segment of the latest apps from the app store."
Apple released iPhone Software 3.0 in June, adding MMS, cut/copy/paste, landscape keyboard, and Spotlight Search among others. To upgrade the iPod touch's OS, one must pay $5 to $10, depending on the time at which they purchased the device.