Ruby on Rails 3: It's much more succinct than Rails 2.
Ruby 1.9.2: It was time to move up from 1.8.7.
MongoDB: I introduced this new technology to the company I work at which has now adopted it for two significant projects. One was the project I researched it for initially, which handles millions of writes per week, and the other is a rewrite of something we used to use MySQL for. It currently has a hundred million or so documents and is going strong. It's new and fun. My collection uses dynamic sharding; I think the other one does as well. One is hosted in our data center, the other is in the cloud. Both are in production and running with 100% uptime so far.
Ruby 1.9.2: It was time to move up from 1.8.7.
MongoDB: I introduced this new technology to the company I work at which has now adopted it for two significant projects. One was the project I researched it for initially, which handles millions of writes per week, and the other is a rewrite of something we used to use MySQL for. It currently has a hundred million or so documents and is going strong. It's new and fun. My collection uses dynamic sharding; I think the other one does as well. One is hosted in our data center, the other is in the cloud. Both are in production and running with 100% uptime so far.