Fifteen years ago, cell phones were the size of your head and owned by only a few people – generally high-powered execs looking to cut a cutting-edge figure while talking loudly behind you on the subway about a deal, merger, or clandestine affair.

Today, Standard & Poor’s estimates the wireless market’s penetration is a little higher – nearly 80 percent in some areas as of July 2006.  Clearly, the vast majority of people in the United States have a mobile phone.

This is bad news, not only for folks who enjoy peace and quiet in places like airport terminals, movie theaters, and restaurants, but also for cell phone providers.  This particular market is reaching a point of market saturation; those who have made it this far without a cell phone are (a) stronger than the rest of us; and (b) not likely to pull the providers out of their slump.

(Don’t be too sad for cell phone providers.  For one thing, the market value for telecommunications is over $200 billion.  For another, while market saturation may continue to be a growth issue, continual updates to cell phone technologies – e.g., cameras, video recorders, mp3 players, in vitro incubators, and cold fusion generators – ensure that they will forever be able to sell a lot to their pre-existing customers.)

Of the approximately 208 million cell phone users in the United States, the fastest growing segment is the youth market: users 18 to 30.  Cell phones are often the only phone these users own, and the primary way they interact with the outside world.  Whether it’s through person-to-person calls, text messaging, music downloads, or internet access, cell phones are de facto mini-computers that function simultaneously as the life blood of this country’s young people.

With no intention of libel or maligning the under-30 crowd, young people tend to amass lots and lots of unsecured debt in the form of credit card debt, followed by student loans and car payments – or, 30 percent of the national debt burden.  Trends in the broader credit industry show that they’re also not so good at paying it back.

What does this mean, both for the cell phone and credit card industry?  Both a (potential financial) blessing and a (potential financial) curse.