In August, I flew up to Seattle to meet with Real to discuss the nascent chess match between Apple and Real. In case you need a refresher, Rob Glaser of Real fired the opening salvo by making his store's music compatible with the iPod without the blessing of Steve Jobs. At this point, Apple has merely rattled its saber, and has yet to release the hounds (read: lawyers) on Real. We'll have to wait and see how that story plays out.

Anyway, after meeting with Real's executives that morning, I broke for lunch with Kevin Foreman, head of Real's Helix division. (Helix is Real's "open, multiformat platform for digital media creation, delivery, and playback.")

We covered a lot of ground that day, but one thing Foreman said really took me by surprise. He said that as early as next year, the bottom could fall out of the MP3 player market. Why? Because people will use cell phones to listen to their music instead, Foreman said.

My reaction was similar to the one you're probably having right now: "Yeah, right. Keep dreaming, dude." Aside from the fact that people love their iPods too much to replace them with phones, his idea violates one of my central theories about portable electronics -- that people will end up carrying two devices, because they need two different batteries. My reasoning is that you wouldn't want to watch movies and listen to music to the point where your battery dies, thus rendering you out of reach of your coworkers, friends, and family. In other words, you need one portable for fun and another one for the more serious stuff of life.

But as we talked Foreman's idea through, I saw that it had some merit. Besides, several phones already support MP3.

If you already own an MP3 player and you're in the market for a new cell phone, you still might want to think about a cell phone with MP3 playback. Right now, an MP3-playing cell phone doesn't store many songs, but wouldn't it be cool to keep a dozen or so tunes on one just in case you find yourself sans iPod with a free half hour, say, in a dentist's waiting room?

So if Kevin Foreman's right, cell phones will start displacing MP3 players next year. One thing that could help facilitate this transition is that Apple announced a deal with Motorola that will let you buy music from iTunes that can be played on a Motorola cell phone in 2005. Nokia quickly announced a similar deal with European online music store LoudEye, while Microsoft's MSN Music division recently followed suit by trumpeting its upcoming plans with cell-phone chipmaker Qualcomm. I bet none of these partnerships will let you actually purchase and download music wirelessly on your phone, because the price of sending that volume of data would erode the slim margins already endured by online music stores. However, the technology of tomorrow could change that.

There are three key technologies that will have to arrive before I'm personally willing to place my chips next to Foreman's in betting that the MP3 player will be overtaken by music-playing cell phones. First, I'll need more storage on my phone, because flash memory players, while great for the gym, just don't cut it when it comes to storage capacity. I want every song with me all the time. Samsung recently announced what it is calling the world's first cell phone with a hard drive. Granted, the SPH-V5400's one-inch microdrive will only have a 1.5GB capacity. However, if you've followed technology for at least six months, you know that everything gets smaller and holds more data over time, so that capacity barrier is anything but permanent.

I'll also need to reconcile the MP3-cell phone theory with the "two batteries, two devices" concept outlined above. Fuel cells will solve that problem, possibly as soon as the end of 2005.

Finally, I'll want the ability to buy songs for my cell without first needing to load them on my PC before transferring them to the phone. This will require wireless connectivity to be as cheap and as fast as DSL and cable Internet access both are today. I'm not holding my breath, but we could get there as soon as 2006, especially if service providers and consumers are tempted into adoption by the promise of wireless music.

For now, don't expect to exchange your MP3 player and cell phone for one device. I'm just giving you sufficient early warning so that you have a few years to get used to the concept of a combination MP3 player-cell phone before it actually arrives on the scene. I know that giving up my MP3 player next year would be quite a shock to the system--and I'd be willing to bet you feel the same way.