palmOne's Treo 600 is the most popular smartphone in the United States.

That's a significant achievement, as the handheld company is up against giants like Nokia, which dominates the mobile device market throughout the rest of the world with its Symbian-based handsets.

Although the Treo 600 is a great product, it is—at almost a year old—getting a little long in the tooth. And as a high-end mobile handset, it is too expensive to appeal to a broad range of people. palmOne has also had well-documented problems keeping up with demand for the smartphone.

These are just a few of the reasons industry experts—not to mention fans of the Treo 600—are eagerly awaiting the next-generation Treo. Although some data about this smartphone leaked over the last few months, palmOne has understandably been stingy with details. Why hurt sales of your current smartphone by offering information about a better one?

Just today, however, the leaky faucet that is the Internet rumor mill spilled some secrets via TreoCentral, an enthusiast site, about a new Treo smartphone. Add this information to what we already know about the next-generation Treo and a pretty detailed picture conjures up right before our eyes.

Here's what we know: Called the Treo 650, the new smartphone will supposedly look very similar to the current model—QWERTY thumb-keyboard and size—but should differ quite a bit otherwise.

Unlike the Treo 600 and its 160 x 160 screen, the Treo 650 will have a high-resolution 320 x 320 display, which should make it easier to read documents and Web pages. The Treo 650 should also integrate Bluetooth, a glaring omission in the current model. Bluetooth would allow Treo owners to use wireless headsets and print to Bluetooth printers, for example.

As opposed to the Treo 600, the Treo 650 should also feature a swappable battery and a high-resolution 1.3-megapixel camera for taking pictures and video. It should run on a 312MHz processor and Palm OS Palm OS Garnet 5.4.

Unfortunately, TreoCentral reports you can't use Treo 600 accessories with the Treo 650. If that's true, it may hurt sales, as some folks looking to upgrade may be loath to lose their investment in their peripherals.

palmOne should ship GSM and CDMA editions of the Treo 650 sometime this Fall.