Google I/O was one of Android's biggest events of the year, with a Mobile track that focused primarily on all things Android, and 22 developers showcasing some of their great Android applications at the Google I/O developer sandbox.

For those of you who missed I/O or could not make all the Android sessions, we're excited to release session videos and presentations from the Mobile track online and free to developers worldwide.

At this year's I/O, we wanted to help developers further optimize their applications for the Android platform by creating better user experiences. Romain Guy explored techniques for making Android apps faster and more responsive using the UI toolkit. Chris Nesladek discussed the use of interaction design patterns in the Android system framework to create an optimal user experience. Since mobile application development is inextricably tied to battery performance, Jeff Sharkey provided an insightful look at the impact of different application features and functionalities on battery life. Taking the mobile experience further, T.V. Raman and Charles Chen discussed building applications that are optimized for eyes-busy environments, taking advantage of the Text-to-Speech library, as well as new UI innovations that allow a user to interface with the device without needing to actually look at the screen.

We also offered a few sessions on building compelling and fun apps that take advantage of the Android media framework and 2D and 3D graphic libraries. Chris Pruett discussed the gaming engine that he built and used as a case study to explain best practices and common pitfalls in building graphics-intensive applications. David Sparks lifted the hood on the infrastructure by diving into Android's multimedia capabilities and expanding on how to use them to write secure and battery-efficient media code.

We also had several sessions that meditate on challenges, best practices, and philosophies for writing apps for Android. Dan Morrill demonstrated multiple techniques for developing apps for Android in different scenarios, to help developers make the right decisions on the right techniques for writing their apps. Joe Onorato talked to developers about leveraging Android's ability to support multiple hardware configurations to make their applications run on a wide variety of devices without the overhead of building a custom version for each. Justin Mattson talked about advanced usage of Android debugging tools in his session and presented real-world examples in which these tools were used at Google.

Lastly, Robert Kroeger returns from the frontlines of launching Gmail Mobile Web for iPhone and Android's offline capabilities and shares the team's experiences in using a portable write-through caching layer running on either HTML 5 or Gears databases to build offline-capable web applications.

We hope these session videos and presentations are helpful to all Android developers out there. Don't forget to check out our newly announced Android Developer Challenge 2 - we look forward to seeing your passion, creativity, and coding prowess come together in the great apps you submit in this next challenge!