If you're anything like me, you've noticed that Internet Explorer 8 and 9 seem to be accompanied by a child process named ielowutil.exe. The file properties description for this process isn't very helpful, and, in fact, might lead you to believe that it has something to do with your computer's microphone!
The file description reads: Internet Low-Mic Utility Tool. This sure sounds like it's doing something with your microphone, doesn't it? It turns out that this is a misleading description.
MIC stands for Medium Integrity Cookie (or so it seems). The Low-Mic process is intended to broker low- and medium-integrity process API calls. It has to do with increasing security (reducing malware attack vectors) in IE8 and IE9.
This MSDN blog entry describes IELowUtil.exe:
So the short answer is that IELowUtil.exe is the broker process that handles operations which require processing at a Low Integrity level.