They are over due for a new iPod. They came out with the 5.5G iPod a couple of months ago, and some people call that it, but I seriously doubt it. I expect that sometime within the next year, Apple will announce a full screen touch controlled iPod with up to 120GB of storage minimum (In conjunction with 720p movie downloads from iTunes).
Regardless of whether or not I'm right, the 30GB iPod as it is now has been out for over a year. Anybody will tell you that the time to buy an iPod is the moment a new one gets released. More than 8 months after that, and you likely won't get your money's worth before being obsolete.