As I said in this thread over here:
The typical tape used in computers is something called Kapton, which is available from iFixit. Electrician's tape is generally resistant to the sorts of temps you get in electronic circuits, and the adhesive is weak enough that you won't damage anything when you remove it. That might be acceptable to you as a jury-rig solution. Apple tapes all the stuff down very carefully, because the cables are exactly long enough to route in their preferred way, and not one millimeter longer. Sometimes you need to tape that stuff down to keep it exactly where Apple wants it. Compare this to a lot of other manufacturers, who have tangles of oversized cables in their boxes, disrupting the airflow and taking up valuable space.
Kapton tape isn't conductive. As long as you're not trying to camouflage a DIY operation to preserve an Apple warranty (hey, you've been messing around inside this thing! Your AppleCare warranty is now VOIDED!), you can pretty much tape down anything you think needs taping. If you're following an iFixit guide, it's usually safe to assume that any Kapton tape you see is the Kapton tape Apple put there in the first place; replace as necessary.
(new comments) Of course, a lot of us don't keep Kapton tape on hand, so we use electrician's tape/masking tape/medical adhesive tape... or even nothing, depending on what works for the moment. I usually try to keep the original Kapton tape as intact as possible, because I'm lazy and cheap. If it sticks when I reinstall it, great; if not, I cuss a little and move on.