Gillette (NYSE:G), the 800-pound gorilla in the razor business, appears to have dropped to 749 pounds, and may be shedding more weight. Blame Energizer Holdings (NYSE:ENR), whose Schick unit is enjoying success with some new product launches.

According to a Wall Street Journalarticle (subscription required), before Schick introduced its new Intuition razor for women in April, Gillette's share of the blade-and-razor market stood at 67.3%. By the end of July, that was down to 63%, while Schick's share had risen to 17%.

Next month, Schick rolls out its new four-blade razor for men -- the "Quattro." (Note: Gillette disputes the market share numbers, as they exclude sales at Wal-Mart (NYSE:WMT), which is kind of a big seller.)

What's all the fuss about these "revolutionary" new razors, anyway? Well, our own Rex Moore asked the same question, providing some amusing answers. But for some more straight-faced explanations, peek at Schick's Intuition page and this article on Quattro.

Investors can learn a lot from these developments. For starters, never assume that your beloved 800-pound gorilla will remain one. Gorillas do have an edge, but they need to maintain sustainable competitive advantages. Next, take a minute to step back and appreciate the power of branding and advertising and psychology.

Razors are, or should be, a commodity -- they're blades on a stick. Yet razor makers continually release newfangled shaving devices, each with groundbreaking technology. And we hapless humans, intrigued and excited by something new and cool-looking and supposedly more effective, often buy in droves. (Of course, if it's all hype, sales will eventually slump.)

Is Gillette's turnaround threatened? Possibly, in the short term. But expect the company to release some fancy new shaving solutions of its own soon enough. Its new three-blade razor for women, the Venus, already appears to be doing well. How well? Gillette announces its quarterly earnings results today.

What do you think? Share your thoughts on our Gillette discussion board -- a free trial is available.