It's just software ... really, it's just software. It's not as important as your family, or your health. It (generally) doesn't kill people or change lives. That kind of thing is left to real people. I will concede that those real people may be using software to help them kill people or change lives but the software alone is neither good nor evil. It does no harm, and in the specific case of software under construction, it can wait a day, a week, or a month.
In this era of fast small deliverables, short timelines, and rapidly changing goals it's easy to forget it's just software. As an industry we are facing decreased demand due to macro-economic pressures, and increasing expectations as our users first become accustomed to, then jaded by, the latest eye candy and features all of which tend to drive us to work as though our lives depended on working. Today’s reality is quite the contrary. Our lives may depend on our not working.
We are nearing epidemic H1N1 virus levels. Entire organizations will close as the percentage of sick employees climbs upward. So whether you are home with a sick child or just feeling ill yourself, do everyone a favor. Stay home and just keep telling yourself ... It's just software.