Nokia has unveiled the latest version of its Linux-based tablet device, this time with a full keyboard.

The N810 is the third version of the Wi-Fi tablet from Nokia. It's expected to become available in November and cost $479.

The N810 is larger than a cell phone, but smaller than a laptop, yet it contains many of the applications typical to both. It includes a Mozilla browser so users can check Web email and visit social-networking sites. The N810 also features a camera, Skype, music player and GPS (Global Positioning System) plus preloaded maps.

While the device comes with a touch screen, like previous versions, this one also has a slide-out full keyboard.

Unlike the iPhone, which also sports a large touch screen, but is so far closed to third-party developers, the N810 is based on Linux and thus open to development. Nokia also launched support services for developers on the platform within its existing Forum Nokia developer community.

Apple has said that it plans to begin allowing third party development on the iPhone starting early next year.

Bloggers had predicted the impending launch of the N810 after a news release said that a forthcoming trade-show party would include demonstrations of the N810 as well as Mosh, a Nokia social-networking site still in beta.

Interest in this type of device - in between cell phones and laptops - may be set to grow. A group of companies, including Mozilla, Arm and MontaVista Software, recently began work on a Linux-based platform aimed at making it easier for hardware developers to create such devices.

Nokia made a stir when it introduced its first tablet because it didn’t include cellular connectivity, an unusual move for the number-one cell-phone maker. The N810, like its predecessor, can be connected to cellular data networks via a Bluetooth connection to a mobile phone.

Nokia hasn’t revealed how many of the tablet devices it has sold.

Nokia also announced that users of the tablets and some of its mobile phones can subscribe to hotspot services from Boingo Wireless. Users will download a Boingo client to their device, allowing them to identify and connect to Boingo hotspots. Subscriptions cost $7.95 per month.