It's anecdata, but JVM tuning comes up far more in Java related conversations I've had than the equivalent in other languages/environments. I'm not enough of a Java expert to fully appreciate why this is.
Well, the JVM has several GCs they have a lot more potential for tuning, and there are many tools to gather data on what the GC is doing and to analyse heap dumps to discover the cause of problems. If you have a language like Ruby which is normally used without a moving GC then there isn’t huge scope for tuning things, but if you have a moving GC then there is a lot you can tinker with regarding region sizes etc.
Part of that is because there are so many options, and since Java is used a lot in software where you care about performance/throughput, you hear about it - just like how you hear about all the different kinds of memory allocators you can write in C.