Most of last QCon's presentations are available for download here.
Highlights to Ola Bini's on JRuby(pdf) and Randy Shoup's on eBay's architectural principles(pdf).
And while we're talking about JRuby, it's impressive how it's becoming a recurrent and big subject. Fast. It had its own small space at big event like QCon and in the last Euruko in Prague, we had a presentation by the JRuby Core Developers Charles Nutter and Thomas Enebo.
Big companies are sponsoring JRuby's development indirectly or directly, like Sun. And other big companies are endorsing its production ready state, like Oracle, which has a publicly available website developed with JRuby On Rails.
It's past the time to give it a serious try...