Why does my MacBook Pro reach high temperatures when running? I have my MacBook Pro sitting on my desk and it's consistently over 160 degrees. It is almost too hot to touch in some places on the casing.
160 degrees Fahrenheit, if it is CPU temperature, is normal for MBP. 

MBPs are designed to run pretty hot, with the aluminum case as the main heatsink the casing gets uncomfortably hot sometimes.

If you want to remedy the problem:


use a laptop stand (I use Belkin Cushtops, they are really comfortable), 
put your laptop on steady, heat-transducing surface (human skin, blankets or soft chairs are bad — wooden/plastic/metallic tables are good),
open up the casing and clean the dust (can make it ~10 degrees Celcius cooler)
or, use less video- or CPU-intensive application =)