Wall Street seemed pretty unmoved by Apple’s announcement of its partnership with IBM, the pre-market share price barely twitching, and analysts pointing to the high level of existing iOS usage in the enterprise sector, suggesting that only trivial gains would result.

Part of the reason for that impression is the hype Apple has given to the penetration level of  iOS devices in enterprise. Back in January, Tim Cook described the numbers as “unbelieveable,” stating that the iPhone is used in 97 percent and of Fortune 500 companies and the iPad in 98 percent.

It doesn’t sound from these impressive figures that there’s much room for growth. But I think the reality is somewhat different … 

First, the metric ‘used in X percent of companies’ isn’t a very meaningful one in isolation. Technically, if a company buys a couple of iPads, Apple can say that iPads are used in that company. We often have no idea whether those Fortune 500 companies have been buying iOS devices in the hundreds, thousands or tens of thousands.

If it turns out that iPads are used only by a handful of senior execs, for example, there could still be massive potential in rolling them out to an entire sales force.

Second, while BlackBerry may be effectively dead in the consumer market, it still has a significant grip on enterprise. Inertia and familiarity mean many large companies have stuck with the dying smartphone platform, but that is unlikely to be the case forever. Pushing iPhones with business apps and proper enterprise-level systems support could, over the course of the next few years, have a huge impact.

Third, while there are markets where iOS is dominant in the business sector, there are others where there is still huge potential for growth. Business Insider pointed us to Citrix data showing that while Apple dominates the Asia Pacific region, it holds less than half the market in EMEA (Europe, Middle East and Africa) – and even in North America, a third of the market remains up for grabs.

(Note that these numbers are for a particular segment of Citrix customers, so are indicative rather than definitive.)

Fourth, as Fortune‘s Elmer-DeWitt observes, while Apple’s previous partnerships with IBM have been less than lasting (PowerPC, abandoned in favor of Intel; Taligent, a joint programming language later abandoned by both companies; and OpenDoc, killed by Steve Jobs as one of his first acts on returning to Apple in 1997), this one is very different in nature, playing to the strengths of each.

Apple is brilliant at developing devices and platforms. IBM is excellent at building and supporting enterprise-scale systems. Put the two together and you have a proposition that is likely to have substantial appeal.

Fifth, expanding iOS usage doesn’t just help sell iPhones and iPads, it also extends the reach of the Apple ecosystem within corporations. The overwhelming majority of the enterprise sector currently uses Windows PCs – and just as iPhones act as a gateway drug for consumers, leading to the later purchase of iPads and Macs, that same potential exists in companies.

I’m not, of course, suggesting this would happen overnight, nor on a massive scale. There are way too many Windows-dependent systems in use in large companies to make a wholesale switch to OS X a practical proposition – not to mention the investment in software. But it does provide Apple with a foot in the door, at least. Over time, it’s likely to have a positive impact.

Sixth, while iOS may be beating Android in the enterprise sector so far, businesses are showing increasing interest in Google Apps as a cost-effective and popular form of collaborative working. Penetration might be limited so far, but Google is pushing hard – and that has the potential to start hooking businesses into the Android ecosystem. Apple needs to defend itself against that threat.

Finally, consumer decisions are often based on familiarity. Many Android smartphone and tablet owners stick with the platform because they know how to use it, and there’s a hassle factor in learning something new. Exposure to iOS in the workplace could well help drive consumer migration to iOS.

The announcement may have sounded rather dry and unimportant in the grand scheme of things, but I think, over time, we might find that it turns out to have been rather more important than many currently imagine.

(Top image credit: TechCrunch Japan)