Go to a store that will let you get your hands on the cameras.
Select any long lens camera, zoom it all the way out and point it at the far end of the store and pick out an object.
Notice how that object dances around on the LCD, in fact you probably can't keep it even near the center of the LCD.
If you are using 10X optical zoom, you are amplifying any camera movement by a factor of 10.
Now switch to the Viewfinder, press the camera to your face and notice that the object is much steadier.
You can improve that even more by leaning your shoulder against a post in the store.
Now you understand the problem and know one solution.
The ideal solution is a tripod.
...People who take those great shots of wildlife, use tripods for such shots.
Having image stabilization will not solve all your movement problems, but it helps.
There are plenty of people successfully using long lens cameras without image stabilization.
I am looking for a x8 to x12 zoom camera and can see that the CNET editors highly rate the OlympusC-770 Ultra Zoom camera in their reviews. However do I need a camera with some kind of optical image stabilisation for shots over x5 zoom to prevent blurry pictures? Do I need to spend a bit more and look at something like the Panasonic DMC-FZ5?