B-tree index is the most common index type. Most if not all of the modern DBMS use it. The data structure and concerned algorithms are really mature, there are about 40 years of development. And PostgreSQL's B-tree is not exception. It's full of complicated optimisations of performance, concurrency and so on. But there're still many ways to improve it. At the conference we'll discuss new features which are already done and ideas for further improvements. Of course it requires deep drive into B-tree internals and I'm going to guide you there.