Application Developers who are well versed in Python programming language and usage of GTK+ toolkit may now create applications for Ubuntu. The best application will be awarded with a System76 Gazelle Professional laptop and people who wins for second and third best app will win a System76 Lemur Ultra laptop and a Nokia N9 phone respectively. The best two application developers who win laptop also win a Nokia N9 mobile. This is a great chance for you to show off your talents. Ubuntu has started the showdown yesterday, that is on June 18th.
Ubuntu gives you three weeks time for developing the application. Once you've finished developing the application, you may upload it by setting up a Personal Package Archive (PPA) on Launchpad. After three weeks, the submitted apps will be reviewed by the Ubuntu team members. Joey-Elijah Sneddon, Founder and Chief Editor at Ubuntu also reviews the submitted Application.
Ubuntu has framed certain rules for joining the app showdown. Developers might abide by it. A best application will be chosen if the app have good looking and friendly user interface. The app should not crash in between or should not have any bugs. The application must be integrated with the operating system, that is it must use quick list, notifications etc. It is better if the application is new to the users, that is the idea of the application should be new. Ubuntu users must feel something new when they use it. 
Certain rules are framed for this competition and it is a must that you must create the application using Quickly, an open source tool for developing applications in Linux platform. When you submit the application, you must setup a PPA on Launchpad. For more details visit here: http://developer.ubuntu.com/showdown/
Participate in the showdown and explain the juries via Google+ hangout.
The application you create must be an open source one to make yourself eligible for the competition. You may use hash tags like #ubuntushowdown and #ubuntuappdev for promoting your application and Ubuntu App Showdown on social networking websites.
Watch the live Ubuntu App showdown Ubuntu App Developer Classroom: http://developer.ubuntu.com/showdown/workshops/classroom/
Chat live with other developers and watch the showdown live.
It is said that, participants will also get a small memento, that is a Ubuntu T-Shirt. The top 3 best applications will be awared with laptops, ultra books and smartphone.