Apple Device Refresh - October 2012
Hi there! This is a rather common dilemma, "now or later". Apple will be updating the iPhone and iPod line in October. Last year, Apple didn't do anything to the iPod Touch, so this year everyone is anticipating rather significant improvements.
In terms of waiting, October is still four months away, which means that your kids are going to get antsy. In the end, the iPod Touch will serve the same purpose; entertainment.
If a device update won't mean anything to you, go ahead. If having new features means a lot, then you should wait.
I hope this helps!