Spyglass was born from our need to quickly build search interfaces. We learned a lot about client-side applications on projects like the Global Patent Search Network, and Spyglass incorporates these lessons into an open-source framework. Spyglass is built on EmberJS and includes components for building modular search applications in Javascript. Out-of-the-box it provides the functionality for search observers that automatically update their linked components. This allows new search results and facets to be automatically pushed to the browser.
2013 saw a lot of growth in client-side search applications for OSC, and we look forward expanding our knowledge in the coming year, including the release of an AngularJS based library "Monocle".
If you're interested in the background of Spyglass, Daniel Beach gave a presentation at LuceneRevolution earlier this year: Building Client-Side Search Applications with Solr »