Yep, cow clippers are used to get cattle "fit" for show. Dairy and Beef cattle are clipped differently.
Dairy the clipping is done on the lower legs as the hair gets quite long and messy around the hocks. Top line, or hair along the back is clipped, brushed up, and hair sprayed to show a straight top line. The tail is also clipped down to the long end hairs, these are washed and fluffed out. Though some farmers actually dock the tails cause they get so messy and can be a source of bacteria. The utters are also clipped. With dairy cattle this is there most endearing factor and needs to be shown off during judging.
Beef cattle I don't know the clipping standards for them. I do know their hair is actually encouraged to grow. If you go to a fair the beef cattle will have huge fans running on them to keep them cool so their hair grows and does not shed.