There is a nice article about Prosumer Digital cameras with megazoom in cnet.com. The race for more powerful zooms is like the race for the megapixels however the quality of the lense will suffer with the increase of its focal range. The article reviewed 5 12x zoom prosumer digital camera and below is their megapixels and focal length.
I own a Tamron 28-300 XR lense attached to my Canon 300D. The lense's 35mm focal length equivalent is 43 - 465mm (10.81x) and I am loving it. The picture does get a bit soft at both edges but I just cannot resist the flexibility of the lense. My second digital camera, Sony Mavica FD-91 bought in 1999 has a focal length 37-518 . But it uses a 1.44 MB floppy as its storage media.