Poll: What was the biggest development news item in 2010?

Was the biggest development news item of the year mobile development, cloud computing, the rise of Ruby, or new frameworks, tools, and libraries?

I think 2010 will be remembered as one of the most evolutionary years for developers in quite a while. Existing tools and frameworks grew by leaps and bounds (Silverlight, .NET 4, and Eclipse Helios come to mind); also, Ruby made its presence known in mainstream development. Enterprises and developers are more willing to put many applications in the cloud when, only a year ago, concerns such as security and latency made most developers I know quite skeptical. And with the release of the Motorola Droid at the end of 2009, the Android revolution began in full, and mobile development went from for enterprise and iPhone developers only to something everyone is looking at it.

There are many other development trends that shifted hard this year, but out of these four, which was the most important in 2010?