Palm is launching a smart phone "companion" called Foleo: a lightweight Linux laptop, that synchs with a Treo smartphone using Bluetooth.

The Foleo, intended for editing email and office documents held on the phone, will work with Treos running the Palm operating system or Windows Mobile. It runs Linux itself, and cost $499 in the US (including a "rebate" of $100). Tonight's launch was leaked early in a Palm press release and then confirmed.

Weighing 2.5lbs, with a 10.2 in screen and a five hour battery life, Foleo is intended as a smaller, faster, alternative to the laptop, which makes the phone the central communication device. It turns on and off instantly, and keeps synchronised ("at the touch of a button" according to Palm). Edits made to documents on the Foleo are automatically made on the paired smartphone and vice versa.

As well as Bluetooth, it will also have Wi-Fi to connect independently to the Internet, as well as a USB port, video-out port, headphone jack, and slots for SD and compact flash cards for memory expansion. It uses solid state storage - and so can turn on and off instantly. Palm did not reveal how much storage it will have, but it will be expandable by an internal Compact Flash card, or an SD card in the slot.

Applications include email, web browser, and editors or viewers for documents including Word, Excel, PowerPoint and PDF files.

Interestingly, it appears to use a standard Bluetooth interface, and Palm says it will work with other Windows Mobile devices besides Palm's own: "Palm believes that most smartphones based on Windows Mobile should work with little or no modification," says the news release, going on to say that it will support the iPhone (or at least "smartphones based on operating systems from Apple"), as well as Blackberries, and Symbian devices. "The Foleo’s synchronisation architecture is open, and Palm expects to work with third-party developers to support as many smartphones as possible," says the release.

“Foleo is the most exciting product I have ever worked on,” said Jeff Hawkins, founder of Palm, and credited with inventing and defining Foleo. “Smartphones will be the most prevalent personal computers on the planet, ultimately able to do everything that desktop computers can do. However, there are times when people need a large screen and full-size keyboard. As smartphones get smaller, this need increases. The Foleo completes the picture, creating a mobile-computing system that sets a new standard in simplicity.”

“The Palm Foleo represents our first product in a new line of solutions that will redefine how people work while away from their desks," said Ed Colligan, president and chief executive officer of Palm. "It starts today with a focus on wireless email, and we expect the Foleo to grow in features and expand its capabilities as the platform grows.”