that's more application specific. they sell such a wide variety of mounts that this is something you need to look into yourself. a few have some really solid 3M "tape" that fixes to a surface. I recently bought one at best buy, mounted it to the top of my helmet and rode through socal canyons yesterday speeds ~60mph, freeways at ~95mph and didn't sweat it at all. Solid mount, solid case, even managed to drop the camera from a 5ft table with no damage to the unit or housing at all.
i guess im not feeling so confident in tape. obviously with tape you can attach it to anything that you dont mind taping. i was curious if the other attachments really work out well. for instance i believe they have a body harness but it would appear to me that this typically would be too low for most applications.