Looking for some pictures which certainly demonstrating this problem on Nikkor lenses. I am about to purchase the lens and want to be able to distinguish.
I own an 18-200 VR and it has a bit of creep. If I have the camera hanging on a strap with the lens pointing down, it will sometimes slowly extend out to 200mm. If I have it at 18mm, it will usually stay put, but if it's at 50mm or so, it may exhibit the creep. It's not a big deal to me.
Here's a video:
The zoom creep occurs (on the Nikon 18-200mm) when the lens is pointing more or less straight up or down. In normal shooting mode, where the camera is horizontal, it won't be an issue.
There is a lock on the lens at 18mm. So you can lock it for walking around.
Mine only creeps when I have the lens cap and (relatively heavy) polarising filter on. With those removed, it will only creep if I really shake the camera.