OK. This is it. Unless something big happens in the next few weeks - and I mean really big, like definitive research linking the iPhone to global warming or prostate cancer – this will be my last article for awhile on what some are calling the most successful product introduction of the 21st century.

But what about the iPod?” you seemed to ask. “Surely the iPod is the most successful tech gadget of the 21st century”.

And, you know what? You’re right, to some degree. No other technological trinket has come to dominate its market like the iPod has. However, when the iPod began shipping in November of 2001, it wasn’t an immediate runaway hit, as the iPhone appears to be. Unlike the iPhone, the first-generation iPod was Mac-only. It was derided by the tech press for, of course, not playing well with Windows, it’s $400 price tag, it’s scroll-wheel-based user interface, it’s size, and it’s hard-drive-based storage. In the first 45 days, Apple sold 125,000 first-generation iPods. Apple probably sold that many iPhones the first day.

It wasn’t until July of 2002 that Apple released an iPod that would connect to a Windows PC, using the established Windows jukebox Musicmatch rather than Apple’s iTunes. It took until June of 2003, more than a year and a half after its release, to sell the millionth iPod. Complete Windows compatibility (iTunes and the iTunes Music Store for Windows) didn’t come for almost two years, and sales have increased steadily ever since. In April of this year Apple sold their 100-millionth iPod.

So what happens to the venerable iPod family now that the iPhone is unleashed? Although Steve Jobs has stated that the iPhone contains the best iPod Apple has ever shipped, is there still a viable, profitable market for standalone, non-phone iPods? I think so, and here’s why.

Although the price of flash RAM (used in the iPhone and the iPod nano and shuffle models) continues to fall (I saw a 12 GB flash RAM drive the size of a book of matches on sale recently for $100), the price for flash RAM in quantities of 30 or 80 GB used in the current “video” iPods is still quite prohibitive.

The iPhone’s operating system and applications software require roughly 700 MB of space. That only leaves a little over 3 GB for photos, music, and video on the 4 GB iPhone. One two-hour movie, purchased and downloaded from the iTunes Store, requires about 1.2 GB of space. You can see that, while either iPhone may be Apple’s best video iPod, it won’t carry much video. You need a hard drive based iPod for that.

Apple’s flash RAM based iPods, the nano and shuffle, are extremely portable, great for use while running, biking, etc. While the iPhone is also flash RAM based (no moving parts to be affected by exercise), it’s bigger than a 30 GB and about the same weight (about 5 ounces). I don’t think many people will jog with iPhones strapped to their arms or hanging from their waistbands.

So here’s what I think will happen. Before Christmas, Apple will release a new generation of iPods. The high-end “video” iPods will have roughly the same dimensions as the iPhone, be hard drive based (up to 120 GB), have even bigger screens than the iPhone, and share the iPhone’s multi-touch interface. To further up the ante, they’ll be able to: communicate wirelessly with a computer; deliver pictures, music and video to your home entertainment system through Apple TV; talk to other new iPods; and, perhaps even have access the iTunes Store to purchase music and video without needing a computer.