For a moment, let us look at the various types of people who buy cameras and how they drive the market. There is the professional photographer who buys high end cameras and lenses - however, in most cases, these do not have any bells and whistles (and in many cases, even things that seem standard in cameras - like an exposure meter). The next audience is that of the advanced or avid amateur (which I consider myself one of) that drives much of the 35mm SLR market - new lenses, more features within the camera body (ohh! neat! grid-lines!) and also willing to spend a few dollars on the camera. Lastly, there is the common consumer who wants to have a camera that you can point and shoot with minimal hassle - buy the camera once and you have everything you need.

For the consumer, enter the ZLR. The name is a visual pun on SLR (which stands for Single Lens Reflex - meaning you look through one lens rather than two as with the TLR (Twin Lens Reflex)) - the 'Z' is an 'S' reversed. The 'Z' also stands for 'Zoom'. These cameras work much as a SLR does in that there is through the lens viewing, and a mirror that flips up during an exposure. However, unlike traditional 35mm SLR cameras, the ZLR does not an interchangeable lens. Instead, a zoom lens is permanently attached to the camera. This lens is often a reasonable (though slow (f/4.5-5.6)) wideangle to telephoto (the widest I have seen on a camera is 20mm, the longest 180mm - though a given lens will only cover a 5x zoom range)

The brand that has explored this the most is that of Olympus - with both 35mm and digital ZLR cameras. From the web site:

No need to carry those heavy interchangeable lenses and accessories anymore. Offering the quality of an SLR camera in a compact, ergonomic body, the easy-to-use Olympus IS-series has all the essentials you need making it the ultimate All-In-One solution.

When looking at investing in a 35mm ZLR camera, one should realize that in all likelihood, you will want something better later around. The ZLR itself cannot be 'upgraded' because if the integrated lens design. You can get converters for it, but never can you go out and buy a faster, longer, or shorter lens. Period. Because of this all-in-one design, it also means that a failure in one part of the camera means the entire thing needs to be repaired or replaced - be it a scratch on the lens or flaw in the shutter.

This is not as much of an issue with the digital ZLR cameras where only fairly expensive (ballpark $2000+) camera bodies allow the interchangeable lens system associated with SLR cameras and the majority of consumers are not interested in spending that much for a digital camera. People have become accustomed to buying a single digital camera that does almost everything and nothing more.