Adobe's website provides a set of tutorials to develop mobile applications for iOS (iPhone and iPad), Android, and BlackBerry Tablet OS with Flash Builder and Flex, or with HTML and JavaScript.
Build apps with Flex and AIR
Step through these tutorials for an intro to Flex mobile apps. Quickly build a simple "Hello World!" app, test it on your device, and then build more in-depth mobile apps.
Build apps with HTML
Use HTML and JavaScript to build and test native mobile apps with Dreamweaver and package them for multiple platforms using PhoneGap.
Developing mobile apps with Flex and Flash Builder
Learn to develop Flex mobile apps with the same ease and quality as on desktop platforms. (Flex 4.5 documentation)