It is likely that an iPhone, and probably iPod touch, update won't be too far away. As ever, we won't know the exact date that the newer model(s) will be launched, but there have been some interesting stories recently:
Apple buying up available flash RAM supplies for next iPhone - AppleInsider Apple snapping up flash memory for new iPhone? - CNET
The
MacRumors Buyer's Guide is advising to wait if possible, as a new iPod touch may be out soon.
My question to you would be how long is a reasonable time to wait and see, in your view, as it sounds like you want to replace your iPod as soon as possible. Can you wait weeks, perhaps a few months? If it were me, I'd wait just to be sure, but it does strongly depend on for how long you are willing to delay your purchase!