" The software running on your doctor's desktop PC could kill you if it displays the wrong notes and causes the doctor to prescribe the wrong medicine - yet this is not normally an application considered safety-critical where special software methods must be used to guarantee correctness."
It's also requires neither a soft nor hard real-time kernel. :-)
[On a complete tangent: Is anyone else getting completely sick of that constantly changing Perforce ad. that adorns the top and upper right side of almost every page on LWN. I find it quite distracting and have to move another window to cover the right side of the page each time I open a new lwn page, so that I don't have the ad. screaming at me all the time while I'm reading! They've been running this ad. for many weeks - it's about time the found a new sponsor. Argghh!]