Related link: http://www.blackberry.com/developers/developerlabs/
If you’ve been looking to develop applications for the BlackBerry but are having trouble getting started, check out the Developer Labs available from the dev section of the BlackBerry web site. These labs walk you through more than just a simple “Hello World” demo (although they start you off with that obligatory example). You’ll find walkthroughs for actual useful techniques like storing persistent data and basic encryption and decryption on the device.
To do the demos you’ll need to install the BlackBerry JDE which has been recently updated to support the location based services of the GPS enabled BlackBerry devices.
You’ll find everything you need to get started developing cool apps for a great device.