Wissner-Gross and Freer has a 2010 paper in Physical Review on Relativistic Statistical Arbitrage [official version, pdf]. It makes the observation that as the propagation of prices and trades reach relativistic velocities, that very relativistic limitation of propagation induces some intermediate locations (midpoints between each pair of the 52 world exchanges weighted by turnover velocity) between exchanges from which profitable arbitrage can slow or even stop information propagation. The...

Scala certainly has a lot going for it these days. They have the enthusiasm of at least a couple of the hottest tech companies out there in Twitter and Foursquare. Even Sony is using Scala in some of its systems. There are at least two fairly usable web frameworks, Lift and Play. Akka middleware provides a scalable lock-free concurrency abstraction. XML support is built-in. Interoperability with Java is standard, thus giving Scala access to important systems and APIs such as Hadoop, JSoup,...

The High Scalability blog has a recent post on probabilistic algorithms for approximate counting. The author unfortunately coined the term "linear probabilistic counter", which corresponds to no results if you do a Google search. The more usual terminology is linear counting (a paper from KAIST gives the original definition from 1990) and closely related, approximate counting. The study of probabilistic algorithms is indeed a growing field. It is also tied to that oft forgotten...