I've always been a big fan of Java, especially since its promise "Write once, run everywhere" comes very close - at least if you compare the situation with the C/C++ world 8 years ago (and take all the libraries into account).

However, this promise nearly killed my Christmas last year. Ever used the new fancy ScheduledThreadPoolExecutor? Nice class. Easy task handling in a multi-threaded application design (at least if you dont try to extend it, but this is another story). I've developed my application on Windows, we did extensive tests in a Linux environment and when we delivered the application to our customer's location Friday before Christmas it crashed quite instantly. Within the logger! What's that?