I seem to be doing more and more with Python for work over and above using it as a generic scripting language. R has been my workhorse for analysis for a long time (15+ years in various incarnations of S+ and R), but it still has some deficiencies. I’m finding Python easier and faster to work with for large data sets. I’m also a bit happier with Python’s graphical capabilities via matplotlib, which allows dynamic updating of graphs _a la _Matlab, another drawback that R has despite great graphical capabilities.