At the moment, we’re working on these features for Brian 1.1.3 which should be coming very soon:

STDP working with connections with heterogeneous delays.
A new RecentStateMonitor for storing only the most recent values of a variable.
A new TimedArray class to make it easier to set the values of a variable in an equation from a precomputed array.
Progress reporting for simulation runs, with estimates of how long the computation will take.

In the medium term, possibly for Brian 1.2, we’re working on:

Support for parallel processing with a GPU - the work in progress on this is already available in the experimental subpackage in Brian.
Support for automatic generation and compilation of C code for nonlinear differential equation solvers.
A subpackage, “Brian hears”, for auditory system modelling, including efficient GPU based filterbank operations.