In a cabinet scenario, you should run your power to one side and your data cabling to another. Another scenario is to run your power in the back and data cabling in the front. Most cabinet manufacturers supply channels for the cabling, others supply just openings, but the main point is to provide as much separation as possible.
In a rack situation, it is a bit easier because you have wire managers to assist with the routing of your data cables. You should have one 10" minimum vertical and one horizontal manager per patch panel. I hope this answers your question.
Should you need more information, or have any other questions, feel free to ask. If you are looking at a particular cabinet or piece of equipment, I will be happy to help with an individual scenario as well.
This was first published in July 2005