A developer was poking around in iCloud settings on the latest iOS beta on his/her iPod touch and was given the option to enable the use of cellular (3G/mobile internet) to sync documents and data. This suggests that the next iPod touch might have the ability to use mobile networks which I can imagine being a huge selling point to some people and make the iPod touch 5G seem a worthy upgrade.
Location Services uses GPS along with crowd sourced Wi-Fi hotspot and cell tower locations to determine your approximate location
This implies that the next iPod touch might also have a GPS chip which would be useful for location based apps as currently they only work based on Wi-Fi hotspots. So no Wi-Fi, no location apps. I can imagine a iPod touch, car mount and a navigation app (eg. the TomTom app) would make for a very good replacement for dedicated navigation/GPS devices and might even be cheaper than the high end models.
No doubt if this is true, we will start to see apps for SMS and other iPhone functions being replicated in the Cydia app store, making the iPod touch closer to the iPhone than ever before.