The presentations and tutorials are starting to become available at the Channel 9 useR!2017 page. There's a wealth of amazing content to explore there already, and I wanted to call out one presentation in particular: Uwe Ligges' keynote presentation, 20 years of CRAN.
There are many reasons for the success of R: the language itself, the mathematical and statistical libraries, the data visualization tools, the community, and many other factors. But in my opinion, the most important factor that has driven the growth of R over the last 20 years has been CRAN. This repository of R extensions has been marvellously successful at enabling the world-wide community of R developers to extend R, and to make their extensions available to R users everywhere with the utmost convenience and reliability.
In the presentation you can see below, Uwe Ligges (member of R-core and one of the first maintainers of CRAN after it was founded by Friedrich Leisch) describes the evolution of the CRAN system over the past 20 years, and gives some insights into how it may evolve in the future. If you've ever used an R package (and who hasn't!) it's well worth watching to appreciate the achievements and dedication of the volunteer CRAN team behind providing one of R's most important features.