We're in the market for a cluster; most of our options are Xeon/Linux, but one is a cluster of XServe G5s running OS X. We're going to run some benchmarks to see how the performance compares, but some in of our group have expressed concern that 'the vast majority bioinformatics software is developed on Linux', and 'there may be a long time lag before new software is available on OS X'. I have never had problems getting software I need to run on OS X, but I wondered if anyone can provide me with examples of applications that won't run on OS X, or are Linux only (only binaries released & no source available). This is only one of the criteria we're judging on, and the performance comparison will be interesting. Any insights on this issue would be extremely useful, though. Thanks, Chris