At the Google developer event in San Francisco, Google I/O, the company announced (among other things) the second Android Developer Challenge. Developers submit apps in the following categories: 

• Education/Reference
• Games: Casual/Puzzle
• Games: Arcade/Action
• Social Networking
• Lifestyle
• Productivity/Tools
• Media
• Entertainment
• Travel
• Misc

Winners receive financial prizes:

Overall (across all categories)

• 1st prize: $150,000 (meaning the overall winner will receive $250,000)
• 2nd prize: $50,000 (meaning the 2nd prize winner will receive up to $150,000)
• 3rd prize: $25,000 (meaning the 3rd prize winner will receive up to $125,000)

Winners will be determined in the fall through a combination of audience (Android user) voting and Google judging. Google is obviously doing this to maintain developer interest and build the corpus of apps that are available to Android users.