Last week, Gartner released cell phone research that, among other things, showed that the healthiest part of the industry is the smartphone segment. The firm reported dramatic results: Overall cell phone sales tumbled 8.6 percent between the first quarter of 2009 and the year-ago quarter, but smartphones rose 12.7 percent during the same period.

The discrepancy is likely to grow, at least if the growth in choice offered to consumers is any indication. NewsFactor reports that Andy Rubin, the Senior Director of Mobile Platforms for Google, told an audience at a conference that he expects 18 to 20 Android-based devices to be on the market by the end of the year. Commentary in the piece suggests that the iPhone may be vulnerable simply because it only comes in one basic package, while Android can be embedded in any number of hardware packages. This suggests a wider variety of price points and far greater overall flexibility.

Even a casual survey of the news suggests one thing: The smartphone world, already competitive, is becoming more so by the day. The Motley Fool’s Anders Bylund suggests that the iPhone may move beyond its AT&T heritage and, consequently, the carrier may look at Android. PC World says that Palm’s Pre – set to launch on June 6 with Sprint – may find a home with Verizon within six months. CNET discusses a scoop that Engadget scored on the expansive list of smartphones that AT&T is teeing up for the next few months.

It’s not surprising that a vast array of phones are being introduced. It also makes sense that the jockeying is so intense. The bottom line is that the focus has moved squarely and completely onto smartphones sector. It’s a bit ironic: Though smartphones still are a relatively small subcategory of the overall cell world, they are in every other sense the main category and engine of growth. They are pushing quaint old regular cells into the also-ran niche category.